I have recently heard it could cause a false positive. It seems to me it could also be stress related since she was moving around, and being treated for worms. I don't think I would worry too much considering she only had two diarrheas. The only thing that worried me about that was that you said it smelled horrendous. Parvo definitely has a unique smell like nothing else. :-/ But to me, it sounds like the vaccine might have caused a false positive.