i think its an ingrowing hair ! they are common in creases . it may have a tiny head and will have fluid build up inside that causes size but do burst or scratch open to reveal a smll curled up hair . x x
Possibly a boil - i heard those are very painful!
I had a boil in a similar area once when I was younger. It is a very common area for this. It was about the size of a quarter and was painful. You could see a DR. about it. Mine went away with some anti-biotics. I also had one that popped like a big pimple on my knee when I was a kid, then I was ok. If anti-biotics don't help, I've heard they can "lance it" and let out the infection. I think the previous poster was right, sounds like a boil. I wouldn't worry about it being from sex.
try soaking it in hot water many times in a day. If it doesn't pop on its own after you do that for 2 days or so, you should see a doctor, he may have to lance it to let the infection out. If it isn't a boil type growth then the dr. will have to remove it & send it out for biopsy. (they do that for many things even when they don't think it's cancerous)Good luck with the soaking,it should relieve alot of your pain.
My mother had a boil once on her upper buttocks. Near the hip like where the waist of your pants hit you. It was about the size of a nickel but as round and protuded like the size of a marble. I remember the pain she was in from this. She finally broke down and went to the doctor and they had to lance it. She said that was painful too, she had to side crooked in a chair, but after the pus came out and it healed she was much better.
Now me I have had something like what you describe only it was not on my buttocks it was more on the vagina(embarrassing I know) I didn't know what it was, although I think it must have been a cyst. It didnt hurt unless I went to the bathroom and had to wipe after urinating. I thought it was an ingrown pubic hair. It got really big but I could not bring myself to go to hte doctor, again too embarrassed. I tried to pop it and nothing would come out but it was a hard knot like a marble. Eventually I left it alone to see if it would heal on its own and it didnt, so I tried popping it again and (this is gross) and this nasty greenish yellow pus came gushing out. It had to of been the infection, it had an aweful smell and it was so disgusting. Sorry for being so graphic. So if you are too embarrassed to go to the doctor like I was try leaving it be for a few days, unless its just too painful to deal with, then use a hot washrag, as hot as you can get it, and put it on the boil, or cyst, then try squeezing it to see if anything comes out. If not then you may have to go to the doctor like my mother did and have them lance it to get the infection out.
Haven't heard from you.Are you any better?
I hope you are better and you've seen a doc. I had one..it grew..it busted..it was gross. It came back, and back. I finally had it lanced. It came back and got worse. It turned out to be an anal fissure. Surgery was no fun, the embarassment factor was no fun, but it had to be done. My doc told me about one lady who refused to come in and had a fissure that was causing a huge zit on her vaginal area. She let it go..got septic, and ended up in grave condition.
Most can be managed with warm/hot sitz baths. I soak in very warm/hot water with epsom salts when they start to emerge. I for some reason have a problem with staff bacteria on my vagina. Nothing I was with with stop this. I do a round of antibiotics when it flairs..then it gets better. It's an on going thing and no one tells me why..just that it is.
A related discussion, lump on bottom-very painful