Have you tried supplementing with digestive enzymes and probiotics? That would be the first thing I’d try. A spoonful of plain canned pumpkin also seems to help some dogs when they’re having a bout of diarrhea. All dogs are different so just because another dog had luck with one food or was determined to be sensitive to a certain ingredient doesn’t necessarily mean it will be the case for your dog. If you do want to try changing something with the food I’d suggest a limited ingredient food (single protein) with a novel protein. Limit the treats you’re feeding to the same protein source as the food until you figure out what’s going on.
