Freaking out I could be pregnant

4 days before period was due I had cramps. That night what seemed to be my left ovary started BURNING on and off like someone was holding a lighter outside my skin in that part. I bled a tiny bit that might. Next morning same burning. Went 18 hours with my menstrual cup and it only filled up less than 1/6. Now I just have VERY light brown discharge. My boyfriend and I have unprotected sex and I'm not on birth control. He doesn't pull out when I'm on my period. What's going on.