The Vet has seen him twice, put him on 2 different antibiotics. While taking the antibiotics, the diarrhea subsides, only to return 36 hours after stopping the medication. The puppy is a Rottweiler, about 13 weeks old, and has been tested for Parvo. We’re worried about him because he is on special food that is gentle for the intestinal system as well, though nothing seems to be working.