Stomach pain & cramping!

My period is due on Sunday, and I’ve been on the Pill for just under half a year and it has worked fine. My boyfriend always pulls out and we are always careful. I’ve been having these AWFUL cramps just where my belly button is and I’m quite concerned. I’m not sure whether it could be a pregnancy symptom - which the chance is quite low - or stress, illness or the fact I just don’t eat a lot. Does anyone else get this???