I think you've pretty much stated everything that I would have told you.
The average estimated risk of infection for a man having penetrative anal intercourse with another man known to be HIV-positive is about 1 in 1500. This is an average, so your risk is significantly less not just due to the brevity of the penetration but also because you don't know that your partner had HIV.
It's not possible to diagnose HIV by symptoms so it's not really worth it to go into those.
I once had a similar experience with a partner who turned out to be definitely HIV-positive and nothing happened. It is scary, but the risk is really not that great and I don't think you have any reason to be concerned. HIV is not an easy virus to catch. You're coming up on 30 days since the encounter, so plan on getting tested at that time. It will give you an excellent indication of your status (the majority of people who get infected will test positive by that time).
Your question was "Is there a remote possibility of me being infected?'
That's what Gail was answering with "Nope."
Obviously, you're worried about this, and I think answer is clear that you feel guilty about having sex with sex workers outside your marriage.
Does your wife know about this? Is this part of an agreement that you have? Because the foundation of a healthy relationship is honesty and trust. Many couples find that strict monogamy doesn't work for them as it does for many others, and so they discuss their wants and needs and negotiate a set of guidelines that allows them to pursue their needs and desires honestly and aboveboard.
It doesn't sound like you and your wife have done this, hence you're feeling guilty - and because you feel guilty, you're afraid of getting a scary disease as a punishment and you're even more afraid of passing this scary disease onto your wife. This is the scariest because 1) It would be obvious proof that you had cheated and 2) you would have harmed your wife in the process. So, you're nervous and scared and freaking out despite not actually being at any real risk in the first place.
My advice would be to stop hiring sex workers and consider hiring a therapist or counselor instead to explore why you are doing this and what isn't working with your relationship. If necessary, couples counseling with your wife may be in order.
Do not go and confess to your wife out of the blue. She may have suspicions, but more likely she doesn't know and this would hurt her more than if you kept it a secret. If you can resolve to stop hiring sex workers, then you can take this as a lesson and move on. If you cannot stop, or you don't want to, then counseling (individual first) would be in order.
I do not consider that there is any realistic risk of HIV from this brief encounter. The possible exposure as you describe it is just not significant enough to warrant concern (especially since there is no guarantee that the woman had HIV to begin with).
What should warrant concern, however, is why you opted to solicit the services of the sex worker in the first place. I take it from the concern you have expressed that this is contrary to the rules you and your wife have established for your relationship. If you slipped this once, you are likely to do so again so I would recommend exploring whatever issues led to this encounter and addressing them as needed.
Given the power of guilt to weigh on the mind and engender fears of retribution, I recommend an HIV test at 30 and 90 days to ease your mind.
The polymerase chair reaction type of test is usually used to measure the viral load of HIV-positive patients. That is to say, it searches for the presence of the virus itself instead of the antibodies produced against the virus.
If you had been infected 10 days prior to this test, it is likely that the virus would have made sufficient copies of itself for the test to detect. So, if this test did not discover an HIV that is probably an indication that there is no HIV to be found.
I would follow this up with an antibody test at 90 days just for closure's sake.
HIV does not cause hair loss. HIV can make it more likely for an infected person to develop skin diseases that can affect the scalp, but that would require the weakening of the immune system to the point where the body can no longer fight off infections.
Some HIV medications, however, CAN cause hair loss as a side effect. Are you HIV-positive? If so, what medications are you taking?
HIV needs come into the body from outside. Primarily, that happens through sex with an infected person. HIV can also be transmitted via exposure to the blood of an infected person. In developed nations, the blood supply is checked for HIV so no one gets infected via blood transfusion any more. The only realistic way that people get infected via blood is sharing IV needles.
So, if you've never had sex and you haven't shared needles, you can't have gotten HIV.