My dog with intolerances had them from the day I got him at 8 weeks old, so I have to assume he had them before that. True allergies usually develop later, but I don’t think that is necessarily the case with intolerances. Take the ingredient list with you to the store and try to find a food that is very different, different proteins and different carbs. Also, get him on digestive enzymes, they help with the gas, and a good multistrain probiotic, they help heal the gut, which is where a lot of these issues start and get worse and worse. If you want a recommendation for those, Swanson’s has a couple of probiotics that are good, Dr Stephen Langer’s and Soil Based Organisms. Their Premium Digestive Enzyme is good too. Mercola has excellent of both, but they cost a bit more.
Keep ingredient lists of any food he has with notes about how he does on them. You can compare ingredient lists and start to figure out what it is he reacts to, so you will know what to avoid in the future.
