This is exactly what I went through with Max when I tried to change his food to Canidae. I thought I was being careful and giving it enough adjustment time but he hated it so then I gave him his old food and I guess I got stupid and gave it back too quickly. He got so sick. Diarrhea every few hours and puking yellow bile. He had me up every few hours at night to take him out. He never asked to go out like that before in his entire life. And he was really gassy. I went to the vet and he injected flagyl which I think he said soothes the digestive tract and also injected an antibiotic. Then I had to give him antibiotic pills for 10 days. I also fed him boiled rice and hamburger for a few days. He got better after the vet visit. I felt terrible because it was all my fault.