pimple in between my butt and vag

Lola

I’ve had this pimple for about a week or so now, it hurts when i wipe really bad. i thought it was just a few in grown hairs or something, then i felt it and it’s a big pimple sized bump. i have been with the same guy for 2 years and we haven’t been too sexual active lately so i don’t think it’s anything like that. i do live in arizona so maybe it’s the heat and sweat in the summer... any suggestions?