this could all be nothing

For the last two years I've had occasional pain in my lower abdomen. It's the worst pain I've ever experienced. I'm not on my period when I get it and I never had cramps before. My periods after I got both control are thick brown blobs. Which I've been told is normal. Period may not come at all or last up to three weeks. And recently where my "pee hole" urethral is black. And some days burns and frequent need to pee.  After sex the next day always have light pink bleeding.