No period this last month, but pelvic pain.

I had PMS symptoms for a whole week. After that was over, my period did not come on the expected date. It's still not here, however, I have pelvic pain. It feels sore inside like my uterus wants to shed its lining. Or I'm thinking maybe it's my bowels. I'm not sure. I also have PCOS too. Any ideas? It's doesn't sound like an ovarian cyst or anything, right?