I have a 3 yr old mini Australian Shepherd. She has done something very similar since we've had her (2 years). She goes through what we call an "erping" series. Like she's about to vomit. These typically happen in the evening and she will walk on me and paw me to wake me up and seems desperate me to take her out for grass. These episodes can last all night and often into the next day.
The vet suggested Pepcid and we have used that with occasional success. I don't know what causes this truthfully, but what I have discovered is that she will do this without fail if she has had cooked meat (of any kind) or too much salt. We rarely gave her cooked meat anyway but once we discovered this we stopped altogether. However, she is a high energy dog and so we let her off leash at the park for exercise and cannot always guarantee she doesn't pick up someone's discarded sandwich or something. Since we've had her, she has been on Merrick grain-free dog food. We give her raw chicken patties (made for dogs) and occasionally raw lamb mixed with her kibble. And for treats, she gets string cheese. No issues with this diet that we've found.
I know this string is old but wanted to respond to the fact that your dog wasn't drinking as much water as he used to. I believe that is probably because you quit giving giving him the dried chicken treats. They drink more with certain dog treats due to high sodium (just my experience).View Thread