What could this pain be- worse during sex?

[paintmeblue719]

For the past few days, I've had a dull ache in my lower abdomen, right around my uterus. I'd not due for my period for another 2 weeks, and it doesn't feel like an ovarian cyst to me. My boyfriend and I started messing around this morning, and for some reason, it was incredibly painful. It felt hyper sensitive in a bad way, and also felt as though I was bruised on the inside. (after a week without messing around, so it wasn't from sex) He brushed my cervix, and it felt the same way. It was very sensitive and painful to the touch. Except for the pain, everything else seems normal. I don't have health insurance, so I need to avoid going to a doctor unless its an emergency. Does anyone have any advice for me? Thanks!
Kidney infection dosen't seem real likely to me. And why would I be sore after not messing around for a week? The pain started on a day when I hadn't had sex.