First, if you have any doubts or concerns about a vaccine reaction, do call and talk to your vet. Never hurts to let the vet know what is happening and get his/her opinion.
That said, what you describe is a very common post vaccination reaction, particularly if the "distemper" shot was a modified live vaccine (which is not really "distemper" ... cats don't get distemper ... the vaccine is a combination of: panleukopena, herpesvirus-1 and calicivirus). Modified live vaccines are the most effective vaccines because they strongly stimulate the immune system. Feeling lethargic, lack of appetite, soreness at the vaccination site, etc are signs of the immune system responding. That's actually a good thing, even though we don't like seeing our cats not feel well.
The same reaction often happens when humans get vaccinations. I've been told that some doctors even suggest giving aspirin to kids before a vaccine to ease some of the post-vaccination discomfort. I remember (back in the dark ages) getting a vaccination for cholera prior to a university trip to India ... and being warned at the time that I'd probably feel "lousy" for a couple days. I recall that I did.
So, mild reactions of feeling lousy for a couple days is common. BUT if it seems more serious than that, and/or lasts more than a day or two, call your vet. Trust your instincts.
If your cat received a 3-yr rabies vaccination ... it is probably a "killed virus" (inactivated) vaccine since all the 3-yr rabies vaccines are ... except for one new "recombinant" rabies vaccine by Merial (which is VERY expensive). Killed vaccines do not produce immunity on their own, since the immune system realizes that something that is dead is not a threat. So, killed vaccines need a chemical additive, called an "adjuvant" that causes inflammation at the vaccination site as a way to wake up the immune system and get it to respond to the vaccine. For a 3 yr vaccine, there is generally a lot of adjuvant in it ... which can contribute to your cat not feeling well. Killed vaccines more often tend to cause an allergic type of reaction (swelling, anaphylactic shock) ... but you don't seem to be describing that.
One thing that you may consider in the future ... give the FVRCP (herpes, calici, panleukopenia ... what you call "distemper") at a different office visit than when the rabies is given. Just remember that when separating any vaccines you MUST wait at least 2 weeks between vaccinations ... otherwise the immune response to the first vaccination may interfere with the response to the second one. But giving them at different times may reduce the amount the immune system is dealing with at one time. It can also let you know which vaccine is causing the lethargy, etc.
I'm not a vet ... but my friend and mentor is Dr Richard Ford, now emeritus at NC State vet school. Dr Ford is an infectious disease specialist who is respected around the world for his expertise in vaccines and vaccination protocols. He has been a co-author of every version of both the AAHA Canine and AAFP Feline Vaccination Guidelines. I can't speak for him, but I've learned much ... and have heard him respond to similar questions many times when lecturing at veterinary continuing education conferences.
I hope that by now you have gotten both kittens to the vet. If you haven't had them in for a check-up before, it is always good/important to have new kittens vet checked. If these are rescue kitties, they would normally need a basic check-up, worming and appropriate vaccinations, etc. Ideally, that is done before introducing a new kitten to the household ... so that a new kitten doesn't bring in an infectious disease or parasites.
Any cat that stops eating and becomes lethargic needs a vet visit ... but it is even more critical for kittens, especially one as young as 7 weeks ... because things can go downhill VERY quickly in kittens.
7 weeks is very young for a new kitten ... and normally should still be with its mother for a few more weeks (ideally around 12-16 weeks of age) to give the immune system time to develop and for the kitten to learn how to be a cat from its mother and littermates.
Immunologically, 7 weeks is a very susceptible time. The antibodies it received from its mother (i.e. if the kitten nursed in the first 24 hours of life) may begin to wane and leave the kitten susceptible to disease. Vaccinations usually begin at about 8 weeks of age ... but even then, there is a period of time for every kitten when the maternal antibodies drop too low to protect from disease ... yet the antibody level is still high enough to interfere with vaccines. The result is that the kitten goes through a "Window of Susceptibility" until it receives a vaccination AFTER the maternal antibodies have finally dropped too low to interfere with vaccine.
If both kittens became sick about the same time, it may suggest something infectious ... another reason for a vet check. Vomiting can also cause dehydration very quickly in young kittens, so one or both may need fluids.
Once you get things taken care of by the vet ... you may want to consider going back to a canned food diet. Canned food is BETTER for cats than dry food. Dry food is high in carbohydrates and very dense in calories which can cause obesity (and diabetes later in life). It is common for cats to have allergies to some ingredients that are commonly found in dry food (e.g. corn, wheat, etc) ... which might be a factor here. In contrast, canned food has added water which is very important for cats ... and canned food, by nature, has higher protein (very important) and lower carbohydrates. So, if your kittens prefer canned food ... it is a good thing. If the anorexia and vomiting started after the diet change, that may be another indication that dry food is not the best for your cats.
But there are myriads of things that can cause anorexia, lethargy and vomiting in cats. The only way to find out what the problem is ... is to see a vet and have some tests done. With kittens, you need to act quickly because things can become serious rapidly.
I'm so sorry you are in this position. I (like many) have gone through similar situations and it is never easy. While the common advice "you'll know when it is time" ... has "some" truth in it ... in reality, I think most of us have a hard time really knowing when it is time. Our strong emotions make objective decisions very hard.
A few years ago, a vet created a "Quality of Life" scale to help pet owners look more objectively at the situation and try to decide when it is time to let go. The scale consists of 7 areas that you score from 1-10 (1 is worst; 10 best) and then add up the total points. If the total is above a certain score, then you may want to wait a bit. It's still a tough decision, but the Quality of Life scale can help you to think through some of the aspects.
The scale is sometimes called the HHHHHMM Scale ... for the seven areas that are scored: Hurt Hunger Hydration Hygiene Happiness Mobility More Good Days Than Bad
Not all are of equal weight ... e.g. the first area, Hurt/Pain, is most important and if a pet appears to be in a lot of pain that can't be controlled, then the rest of the areas on the scale don't really matter.
When you first mentioned that he had lymphoma ... I thought things might not be so bad. I know there are different types of lymphoma, but with some types (particularly the fast-growing lymphomas), some cats will respond well to chemo and have 1 or more years of remission. In general, chemo given to pets is more mild than what humans get, with fewer/more mild side effects ... since chemo for pets is generally given with the goal of making them feel better for a longer time, not large doses of chemo in an attempt to cure it. Chemo might be worth a try.
But when you mentioned that he is FIV positive ... then I admit (though I'm not a vet!) that the future sounds pretty bleak. If the FIV is active, it can severely suppress his immune system ... and make it difficult to treat or control the cancer (as far as I know). This is, obviously, a talk you need to have with your vet who is familiar with your cat ... and who is in the best position to advise you. Hopefully you have a good relationship with your vet. With my last cat (who died from pancreatic cancer at age 18.5), I was very lucky because both her regular vet and her internal medicine specialist became very good friends of mine ... and they promised to let me know when they felt she was suffering and it was time to make the decision. In the end, she went downhill very quickly the last week and I knew it was time. Perhaps I waited too long ... but until the last day or two, they felt she had a good interest in life.
Good luck with this tough situation. Remember one thing above all ... what matters most to your cat is your love! Your cat will know that whatever decision you make, and when you make it ... it is because you love him and want to do the best for him. In that respect, you can't make a wrong decision. Your motivation is love ... and your cat knows that. He is blessed indeed!
This is a bit off-topic for a board on pet health issues. But to answer your question (who doesn't like to talk about their own kitty!) ... my cat, "Lisabelle" is a pedigree RagaMuffin. She was actually a gift to me from one of the founding breeders. Lisabelle is a "blue-cream and white", i.e. a dilute tortie and white.
The RagaMuffin breed was first registered as a breed in 1994 in the American Cat Fanciers Association (ACFA) and received full breed "championship" status in ACFA in 2001. The breed was first registered in the Cat Fanciers Association (CFA) in 2003 and received full championship status in CFA in 2011.
The breed shares some common origins with the Ragdoll ... i.e. the cats bred by Ann Baker in California in the 1960s. But it is a separate breed and developed differently with a larger gene pool ... which allows for a wide range of colors and patterns. Similar to the Ragdoll, "Muffins" are very people oriented and have a tendency to "flop", i.e. go limp when picked up (not true of all RagaMuffins, but of many). The coat is what I love the most. Lisabelle's coat is medium in length and extremely dense (it is hard to find skin), yet never mats ... and is the softest thing I've ever touched, like rabbit fur. Again, not every Muffin has the perfect RagaMuffin coat ... but Lisabelle does, and I love it.
The breed club started by the founders is: RagaMuffin Associated Group (RAG). Our website is in the process of being redone but you can google the old one. We also have an active Facebook page. You can learn more about the breed from some of our breeder websites.
That said ... I also care for 3 "unowned" apartment complex cats (one of which is currently at NC State vet school having the radioactive iodine treatment done to cure her hyperthyroidism). Those three chose me and are also wonderful, loving cats. So, I highly recommend RagaMuffins and know many of the breeders ... but you can also find wonderful cats in shelters as well.
Sorry to be so long winded ... just trying to be helpful.
Let me add another reason that many would advocate a canned food diet:
4. Canned food can be helpful when having to give certain medications or supplements to cats. That tends to become more of an issue as cats age and have health issues. It is easier to mix some things into food ... like the amino-acid, L-lysine, if a cat has herpesvirus, a common cause of upper respiratory problems ... or probiotics, which might be something you want to give if your cats have some intestinal issues, etc. I've heard many people lament that they couldn't give a pill to their cat ... and since the cat would only eat dry food, they couldn't put the pill in food or something like a pill pocket.
For all of those reasons, I (and most of the experts) think it is best to give either a canned food only diet, or at least some canned food on a regular basis. The brand is not that important, though I always look for something that is high in protein and with as little fruits/vegetable as possible. I avoid the "chunks and gravy" type canned food because the gravy is high in carbs. Actually, even some of the veterinary nutritionists agree that one of the better canned foods are the Fancy Feast "pates" ("Classic" type). I feed that to the outdoor community cats that I take care of. A friend of mine who is a top veterinary internal medicine specialist actually feeds his cat Friskies canned food and she does great on it. So you don't have to get an expensive designer food.
If you are looking for another dry food ... I know of a number of people who really like one called "Young Again". I'm not sure it is available in stores but you can get it online: https://www.youngagainpetfood.com/ It even claims to have a "zero carb" dry food ... though I still don't know how that is possible. But many feel their cats do very well on it. Personally, if your cats like canned food, I'd keep giving it. If your cats have some intestinal issues, giving probiotics in the food may be helpful. It isn't a treatment for current problems but helps to build up the good bacteria in the gut which can help prevent future problems. It is more of a long-term help.
Sorry for the long reply but wanted to help since the vets here seem to have disappeared.
I'm not a veterinary nutritionist, so can't give an authoritative reply. But one thing I've learned after years of hearing people talk about what they think is the best and worst foods for cats ... is that every cat is different. For nearly every brand of food, some cats will do very well on it, and others may get sick or just not do well on it. Given that you had more than one cat vomit after eating Proplan, it only seems logical to try switching to another food. Even if other cats do well on Proplan, your cats do not seem to ... assuming it is the reason for the vomiting and/or pancreatitis, etc.
That said ... if your cat is eating canned food now ... that's GREAT! My "hobby" is listening to talks given at veterinary continuing education conferences by some of the top veterinary specialists and researchers. There are varying opinions among them, but the majority would encourage feeding a canned food diet (and even better, with added water) ... over a dry food. There are several reasons for that:
1. Dry food, obviously, has very little water in it. Cats began as desert animals and as a result have a very low thirst drive. Cats that eat dry food will drink more water, but it is felt that they do not (and can not) drink enough to make up for the lack of water in their food. Many cats do well on dry food because they can concentrate their urine well when young and healthy. However, as they age and become prone to kidney disease, the lack of water ... and likely chronic sub-clinical dehydration ... can increase the progression of kidney disease. Also, hydration is very important for pancreatitis and a dry food diet may contribute to bouts of pancreatitis. The concensus among most experts is that we need to get as much water into our cats as possible ... and feeding a canned food diet (with added water) is one good way to do that. For cats with any type of kidney or urinary issue, the first thing a vet will do is to recommend a canned food diet, for the added water. Why wait until a cat develops kidney disease?
2. Dry food, by its nature, is high in carbohydrates because it generally requires carbs to make the pieces of kibble retain their shape. More and more of the feline specialists and nutritional experts (like Dr Susan Little and Dr Debra Zoran, among others) are advocating a high protein, moderate fat and LOW carbohydrate diet for cats. Cats are obligate carnivores which means that they need an animal diet (meat, internal organs, bone, etc) to get their needed nutrition. They can process some carbs and vegetables ... but not as efficiently and they cannot get all the necessary nutrition (like taurine). Their natural diet of small prey is high in animal protein and very low in carbs. But dry food usually is quite high in carbs and low in protein. Canned food, no matter the brand, usually has higher protein content and lower carbs than dry food. Whatever food you feed, it is best to look for something that is higher in protein.
3. Feeding canned food can better control a cat's weight. Obesity is often a problem with cats fed a dry food diet that they can graze on throughout the day. Dry food is VERY calorie dense (because of the lack of water) and cats can easily eat more calories than needed. Canned food has water that helps fill the cat up and eat less calories. Also, protein helps make a cat feel full ... and since canned food has higher protein, a cat will feel full sooner and less likely to over eat. Also canned food is usually fed in "meals" and not left out to graze on during the day ... again reducing calorie intake.
I'm running into the letter limit for this reply ... so let me continue my response in another reply ....
Sorry for the long reply, but I suspect you want this info. So, continuing my reply above ....
The giving of lysine for herpes is falling out of favor with some experts now because of a few studies that have shown that it didn't help cats with an active infection. But it appears to be quite safe to give long-term to cats and may help some. As mentioned above, some, like Dr Ford, feel that lysine may help keep herpes in a latent (dormant) state, thus reducing or eliminating future flare-ups.
The good news for herpes is that there IS an antiviral medication that is safe to use in cats and has become the "go-to" medication to treat active herpesvirus-1 for most experts. It is called famciclovir (brand name is Famvir). Nothing will cure herpes, but famciclovir helps many cats to get it under control and stop the sinusitis. For cats with ocular signs (e.g. conjunctivitis and eye ulcers), another antiviral, cidofovir, can be reformulated by a veterinary ophthalmologist to use as a topical eye drop.
So, I'd encourage you to ask your vet about trying Famvir. I think it is okay to use in a 4-month old kitten, but that is something to ask your vet about. Famvir will not help if the virus is calici, but it seems to be worth trying since it may be herpes.
Another thing to be aware of is that it is common to have a secondary bacterial infection. It is made worse because the structure of the nose contains many microscopic bones, called the turbinates that help filter the air ... and herpesvirus can permanently damage the turbinate bones in the nose. The result is that it produces an environment that promotes bacterial growth. Nothing can be done to correct the damage to the turbinates ... and it makes cats susceptible to bacterial infections for life. Antibiotics can help while they are being taken ... but once stopped, the bacteria repopulate. As mentioned above, using an intranasal vaccine once or twice a year may help some cats. The intranasal vaccine stimulates a local antibody response in the mucous membranes in the nose which can help control the signs of sinusitis. Hopefully, your kitten won't have that problem, but if you have ongoing problems, that may be the cause.
One final note. You mentioned that your kitten was up-to-date on vaccines. Was the final kitten series dose given at 16 weeks or later? That is very important, particularly for the panleukopenia portion of the vaccine. Studies have shown that when the last kitten vaccine is given at 12 weeks, about a third do not develop antibodies to panleukopenia (which can be fatal). The reason is that there is interference from the maternal antibodies that the kitten receives from its mother when nursing during the first 24 hours after birth. There can be interference with vaccines until 15 weeks or so. Thus it is recommended to give the final vaccination at or after 16 weeks. Also, a modified live vaccine should be used ... not a killed virus ("inactivated") vaccine. Modified live gives better protection with a quicker onset of immunity.
Even when up-to-date on vaccinations for herpes and calici ... cats can still become infected. No vaccine for herpes/calici will prevent infection, nor prevent shedding of the viruses (which could infect other cats). The vaccines are said to give "non-sterile" immunity which means that they don't prevent infection but will lessen the severity of symptoms once infected. Since herpes and calici can be fatal in some kittens, the vaccines are very important to give. Just wanted you to know, if your kitten has herpes or calici ... it is not a failure of the vaccine.
I'm not a vet, but I am friends with and mentored by one of the top veterinary infectious disease experts in N America, Dr Richard Ford, now emeritus at NC State. He continues to be full-time on the veterinary continuing education circuit where he regularly lectures on feline upper respiratory diseases. He is also one of the top experts on vaccines and vaccination protocols, and a co-author of all versions of the AAFP Feline Vaccination Guidelines. I can't speak for Dr Ford, but I can share some of what I have learned from him. I've attended his talks numerous times and had many hours of conversation with him. Hopefully, I've learned something.
Up until your final sentence, it sounds like an upper-respiratory infection (URI). Your last sentence suggests that there may be some lung involvement if she is having difficulty breathing. If your vet hasn't done so already, an x-ray would be helpful to check out the lungs, if she also hears lung sounds on exam.
That said, I'll share some info on URIs which seems to be a component, if not the primary issue.
It is felt by the experts that the vast majority (ca 80% or so) of URIs in cats have a virus as the primary problem ... and then may have secondary bacterial infections. The two viruses that are extremely common in cats are feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV). Both can cause sneezing and sinusitis. Herpes tends to be involved when there are also ocular signs (watery eyes, and in more severe cases, ulcers on the eye) ... while calici is more often associated with oral ulcers. But Dr Ford has said that it can be difficult, even for the experts, to tell if herpes or calici is the cause, based on URI signs.
Antibiotics will not work against any virus ... antibiotics only treat bacterial infections. That can account for the lack of resolution with the antibiotics. But since there may be a secondary bacterial component, antibiotics may help to control that part of the problem.
Unfortunately, if the problem is calicivirus, there is no medication to treat it. There are drugs that will kill calici, but they also kill the cat ... a bit counterproductive. With calici, one can just give supportive care (e.g. flushing the sinuses to clear out some of the gunk). The good news is that most cats will clear the calicivirus on their own after a few weeks. A small number are calici carriers and may have long-term problems. One "treatment" that works for some cats is actually just giving them an intranasal vaccination (i.e. either the Heska or Zoetis/Pfizer 2-way intranasal vaccine for herpes/calici). Here is a link to a Q&A on Dr Ford's website where he addresses this. The website has gotten out-of-date but this info is still current. http://dvmvac.com/QAvacBB.shtml#fcore
With herpesvirus, nothing will cure it and nearly all cats infected have it for life ... BUT a good immune system can put it into an inactive "latent" state in which there are no signs of disease. It is common for stress to reactivate (recrudesce) herpes ... which is why kittens often have flare-ups soon after they are rehomed, which is a stressful event. The good news is that there are some treatments for it that won't cure it but can help to get (and keep) it in its latent state (no symptoms).
The fact that your vet gave you Viralys suggests he/she feels the problem is herpes. Viralys is a form of the amino acid L-lysine. Lysine helps by slowing the replication of herpes. In a mild case, it can be enough to give the immune system a chance to get herpes under control. But in severe cases, it doesn't usually help a lot. Dr Ford feels that lysine is better at keeping herpes in a latent state, than it is in treating an active flare-up. Many cats with chronic sinusitis from herpes are given lysine for life (it can also be given as a powder mixed into canned food).
Ooops, running out of space, will continue in next reply.View Thread
I'm not sure where milessmith is getting his information. I can say that the veterinary experts who wrote the 2011 AAHA Canine Vaccination Guidelines (which is used as the standard in N American veterinary medicine) would NOT recommend a Bordetella bronchiseptica vaccine be given ROUTINELY to dogs every six months.
One of the co-authors of those Guidelines, who lectures at vet CE conferences regularly on vaccination protocols, Dr Richard Ford (emeritus at NC State vet school), is a friend and mentor to me. I have listened to many of his talks, read many of his published articles and talk to him often about vaccinations. I can't speak for him, but he feels I have a good understanding of the issues.
1. Bordetella bronchiseptica (Bb) is a NON-Core vaccine ... which means that it is only recommended if a dog has a known high risk of exposure, e.g. about to be boarded at a kennel, regular time in a dog park, dog shows, etc. It is not recommended automatically for all dogs.
2. There are three different types of Bb vaccines ... with three different routes of administration: injectable, intranasal, oral. The immune response and booster intervals differ based on the vaccine used. However, in all cases, studies have shown that the duration of immunity (DOI) is at least a year. Of course, not all dogs respond to vaccines in the same way and there are no guarantees. The AAHA Guidelines recommend boostering "annually or more often in high risk animals".
It is critical that Bb vaccines be given ONLY by the route of administration that the vaccine is labeled for, ie, NEVER inject an intranasal or oral Bb vaccine (can result in death) or give the injectable Bb in the nose or mouth (will not give protection).
a) Injectable ("parenteral") - The only injectable Bb vaccine is a killed ("inactivated") vaccine. Immunologically, the initial vaccination (i.e. first time the dog has been vaccinated for Bb, regardless of age) requires a SERIES of TWO initial doses, given 2-4 weeks apart ... plus a week to respond, before there is immunity. A dead (killed/inactivated) bacterial vaccine is not very immunogenic and is generally not recommended EXCEPT for dogs that are very aggressive when giving the intranasal (or oral) vaccine. Giving a shot is preferred to having a vet lose a hand trying to put vaccine in the nose.
b) Intranasal (IN) - This is a modified live ("avirulant") vaccine that is preferred by most of the experts. It can be given at a younger age (as early as 3-4 weeks) and requires only a single initial dose which can give immunity as quickly as 72 hours. IN vaccines give a better local (in the nose) immune response which is beneficial for an upper-respiratory infection. Also, most IN Bb vaccines come in combination with at least Parainfluenza vaccine ... which is another cause of "kennel cough". Giving both Bb and Parainfluenza as an IN vaccine is felt by most to be the best way to give protection to at-risk dogs.
c) Oral - The oral Bb vaccine came out after the 2011 Guidelines were published. It is also an avirulant live vaccine and shares characteristics with the IN vaccine (but is different, and formulated to work through absorption by the mucous membranes in the mouth/cheek). Last I heard, the duration of immunity was not known, but annual boosters are recommended.
Remember also ... there is no single thing that is "Kennel Cough". The experts now prefer the term "CIRD" (Canine Infectious Respiratory Disease) which can be caused by a variety of viruses and bacteria ... most of which do not have a preventative vaccine available.
Bb is non-core and vaccination is recommended only when there is a high risk of exposure. Even then, generally boosters are recommended annually, unless, perhaps, a dog is entering a shelter or kennel with an active Bb outbreak, then more frequent boosters may be recommended.
The key to FIC seems to be STRESS. Dr Buffington and Dr Chew (and others) have shown a direct connection, though the exact mechanism is still unknown. Dr Chew likes to emphasize that they believe that FIC is more of a neurological disease (how the brain responds to stress) than simply a bladder problem. For that reason, Dr Buffington coined the term "Pandora Syndrome". It is felt that it may be a factor in other chronic problems common in cats, but for most, the bladder effect is the first noticed ... i.e. when cats pee outside the litterbox or make multiple trips and have bloody urine.
What is known is that cats prone to FIC have a physically different reaction to stress. In normal cats, stress begins a series of hormonal responses that activates the "sympathetic nervous system" (SNS) ... which is what causes the "fight or flight" response. For normal cats, once this is activated, it is also quickly turned off. That results in the sudden burst of energy that we all experience when scared or startled and then a return to normal.
But for FIC cats ... there is a problem and the SNS does not get shut off properly. The SNS releases a hormone called norepiniphrine. In FIC cats, there is a continued presence of norepinephrine throughout the body. It has an effect on the cells that line the inside of the bladder and normally cause a mucosal layer that protects the bladder wall from the noxious urine. The norepinephrine causes changes to those protective cells and they become more porous and allow urine to contact the inner bladder wall ... resulting in inflammation, and also increasing and activating nerves and pain receptors ... hence the pain of cystitis.
While the exact mechanism is unknown, it is interesting that research has shown that cats that are prone to FIC have smaller than normal adrenal glands. While the glands are structurally okay, it seems to cause some adrenal insufficiency that may be a factor in FIC. Dr Buffington has a theory (not yet proven) that pregnant cats that become stressed at the point when the adrenal gland is forming in the fetuses, may be the cause of the smaller adrenal glands and the kitten's tendency towards FIC.
What Dr Buffington and Dr Chew have discovered is that by controlling the stress, the frequency of FIC episodes diminishes or disappears. The trick is identifying the source of stress and correcting it. That is what they try to do with the IndoorPetInitiative website.
One area of stress that is sometimes overlooked is the stress of the OWNER. Cats easily pick up on stress of their humans and become stressed. It has been observed at vet schools that just before exams, there is an influx of cats with FIC that belong to the vet students. Dr Chew comments that for every holiday for which Hallmark has a card, there are increased cases of FIC (because of stressed out humans). Moral ... take care of yourself, too!
Most episodes of FIC will resolve on their own in 5-7 days without any other treatment (if the stress can be controlled). So, some think that antibiotics help when in reality the FIC would have resolved without them. Most would recommend giving a cat with active FIC some pain medication (buprenorphine, brand name: Buprenex is commonly used).
Increasing the water intake is always beneficial in order to keep the bladder flushed out and dilute the urine to make it less noxious. It also reduces the chance of plugs or stones forming because the urine doesn't sit in the bladder so long. Thus, if your cat will eat it, any canned food with added water is better than a dry diet.
Guess that is enough for now. I hope I've helped a little. Sounds like stress is a factor for your cat with the new cat. If that relationship can improve, the FIC may also improve.