The Very Top, Where ( Excuse My Term) My Butt

The very top, where ( excuse my term) my butt crack begins is extremely swollen. It's not a cyst, it's more like both sides of my cheeks are hard and swollen and have a bit of a welt like appearance. It is very painful to sit or walk and the pain is similiar to burning or something biting me. It suddenly appeared out of the blue and I'm currently in college, hundreds of miles from home. Help would be appreciated. P.s. I'm female.