I had just posted about a red irritated area between my buttocks. It is a large, bright red circle surrounding my anus, and I can tell it's very irritated. It looks like a bullseye around my anus. Does this sound like a STD to anyone? I had a fair share of diarrhea yesterday, and I had anal sex, but it was almost a week ago, but it was protected. I don't know what this is - please help!!