So my boyfriend and I had unprotected sex last weekend (April 15th-17th). We didn't use a condom and I didn't take birth control. I took two birth control pills Monday night (April 16th. 48 hrs. after unprotected sex). And two more pills Tuesday night (April 17th). Is there still any chance that I could get pregnant. And last night my lower back was killing so I took two ibuprofens and they didn't help. My back still hurts today and my stomach is feeling weird around my belly button and ovaries and I feel a little naseated. But I did however start my period last night too. Could this be an early sign of pregnancy and can you get pregnant while on your period?