Me and my boyfriend have been having unprotected sex well anyways yesterday i started to cramp in my lower back and front. and then i had light brown discharge(which has never happened before). only alittle bit. it seemed to last only a couple minutes but today ive been cramping. my period last month was on the 16th, and usually last 5 or 6days. so i was wondering if this could mean pregnancy or just my period coming?