My boyfriend and I have been sexually active for about two months now and were both virgins before this. We have always used condoms and it has always been enjoyable for both of us. However, many times after we have had sex I feel a dull ache around my lower abdomen or lower back area. I usually notice it within a couple of hours after sex. There have even been times when my stomache got upset afterwards and I have had pains from gas or simply got the runs. It is both uncomfortable and embarrassing. I was wondering if this is normal. What could be causing this? Is there anything I could do to fix it?