What is this ?! irriation near rectum/?

i'm 19 , female, in college. a couple days ago I noticed a pimple below my , kind of off towards my thigh and didn't think much of it, but now i have something going on below my , mostly in the rectum area. the area looks irritated and i have a few bumps. i do not know if they are pimples or what. they do not appear to have any discharge. when i wipe after going number 2 i experience a lot of discomfort. it is slightly itchy and painful. i have never had anything like this happen to me before. the last person i was intimate with does not have that i know of. when i try to research this, i get everything from laundry detergent/soap issues, chafing, , to fungal infections and it's alarming.