I think my cervix is swollen or something.. And I'm having some weird symptoms. Any help?

I have been on birth control for a couple of months now, and my period was this week. A couple of weeks ago my boyfriend and I had sex without a condom, and I have been very worried about pregnancy.

I got my period this week, but the flow was very light, and the substance was very brown and very "chunky" almost.. Not completely fluid.

Now it seems there is something swollen inside. When I urinate I can feel it, and I have done some physical investigation. There seems to be a large lump inside.. could my cervix be swollen? Has this ever happened to anyone else?

Could it be possible that I'm pregnant? I did take a test today, but it came up negative. I will probably wait a week and take another test just to be sure. I may have to go to the doctors if I can't get some answers here.