IUD question!!

I've looked around online and don't have a doctor to call to ask and I'm sure it's nothing, but I got the skyla IUD in September and I had a period every month following...some were less bleeding and more spotting and I didn't get one in December! It should have started 4ish days ago. I've had insane cramps and extremely light spotting for an hour a couple days ago. I was just curious if this is normal??? I know everyone reacts differently but could this just be my period slowly stopping altogether? Or should I be worried??