SKYLA Help!

So ive had my skyla in for over 3 months now and my period is irregular as expected. I just finished my period ob friday. Today im at work with the worse pain/cramping in my uterus/back. So much i cant move. It feels alot like when you first get it put in. I checked to see if my strings were there and cant find them. Im really worried something is wrong. Has anyone else experienced this!!