Niggly sickening pain

So my daughter is now 13 weeks old. When she was 7 weeks old me and her dad had unprotected sex, 2 days later I had a VERY heavy period (first one since she was born), 4 weeks later, but 2 days early I took another period I thought could maybe be spotting because it was light and only lasted 2 days and from it I've had a lot of cramping, and slightly sore breast, but over this last few days I've been having a sharp niggly cramping pain in my left ovary area, that is actually making me feel rather sick. Could I be pregnant? I need to test, but have no idea what this pain could be.