URGENT!

Been taking my sugar pills for my BC. Every single time my period comes the 4th morning like clockwork. It's the 4th day and I'm just cramping really bad. That's all. I use the pill perfectly so I don't think it's pregnancy. Also, the last 3 packs I purposely skipped over my placebo pills, could that be why I'm late?! I need help to calm my nerves.