Hi there and thank you for your question. I am a licensed veterinarian and would be happy to assist you. Green color in the stool is a sign that it is passing through the body faster than normal, and is not a cause for concern. Puppies have very sensitive stomachs and intestines, and it can take them weeks sometimes to get back to having normal stools after an episode like this. As long as the diarrhea is not liquid and he is eating and playing normally, I would continue to give the medications as prescribed and would not worry too much. If he stops eating or starts acting lethargic or the stools become liquidy, then I would recheck with your vet and bring a stool sample. At this time, if your vet did not diagnose a parasite, he should not pose any risk to other dogs. Hope this helps... best of luck.