Painful bladder?

Soo about a year ago after I had sex I started having to go to the bathroom very frequently. Wasn't pregnant or anything.

Throughout time sometimes it was really bad and sometimes I felt okay. No pain though.

So about a 9-10 months later I got an IUD and they tested my urine and found nothing.

Then a month or two later I went to the doctor and again they tested and just as before nothing came up...

Then after the IUD I started having to go even more and now (doesn't hurt when I urinate) my bladder itself hurts like the front of my pelvis when my bladder is "full". Sometimes it's not very full at all and after I pee I still feel like I have to go. And also I get sharp tummy aches after having sex if my cervix was hit.

Anyone know what could be going on? It's very uncomfortable.