Iud pregnancy

Ok so I got my skyla iud 3 months ago since then I have been having unprotected sex because my doctor said I could and I know you can still get stds. My periods are always irregular and it says mines 2 days late but yesterday I had the worst cramps and I woke up and there was this weird light discharge mixed with blood. Could that be a sign of pregnancy? Or is that just meaning my periods about to start? I'm so paranoid someone plz help me! I also feel very nauseous but I think that's my anxiety