My period was late this month, before it started I had tingly pain especially in my thighs and down my legs and a pressure type feeling in my abdomen. I'm on day 4 of my period and the pain has been awful. The flow has been alternating between heavy, light, and "OMG where is all this coming from". I've never had this much pain with period. Right now my legs are burning, my pelvic area hurt, my back hurts. What could this be caused by?