i dont know if this will help you or not, since you have already been to the vets. My baby , Buddy when we got him at age 7 weeks from our shelter, had runny diarreah andwhen i took him back to be checked after two weeks of it, they suggested i change the food i was feeding. I am now feeding him chicken soup for the cat lovers soul, and (knock on wood) dont have that problem anymore. I was feeding purina kitten chow...yuck! so, maybe this may help you. ps. They also said if you feed canned food..if it goes in wet, it will come out wet (mushy).