Period question

Okay this is my first time on this app and I got it to track my period well im 19 I have a 13 month old and I have the iud in and I'm on my period now it's my 2 bs day of it and I've been cramping and It feels like I have to pee like every 5 minutes well when I try only a little comes out but if feels like my uterus has a lot of pressure it has never done this before!? So does anyone have any idea why I am having so much pressure ??? Can anyone give me their opinion on this on what I should do?!?