Hi doctors. i m a 20 years old, female, and last night i had protected sex with a friend. i very recently just got off of medication for a vaginal infection called metronidazole which i believed worked... but today i saw that there were small red bumps on my bum ... they don t seem to itch but they are a little bit tender to touch ... theres about eight of them in a line close together on one side, and a few on the other side of my bum, they kind of resemble a rash ... could this be an STD? can it even occur 10 hours after sex? or is it something else?