Help! IUD Worries

So it’s a weekend night, so I can’t talk to any doctors, but am concerned.

I got an IUD 1.5 months ago and everything has been interesting, but the last two days I’ve been cramping and feel a lot of pressure and having gas and weird discharge. I’m due for my period but haven’t started and last had a spotting period on time. The strings are in place when I check. Could it just be my period or could something be really wrong? I have an appointment to check it in two weeks