On Birth Control... light bleeding and cramping

I am on my second month of birth control pills. The first month, I bled a little...but it was right when my period should have been. This month, I had sex on the 6th day of the pac. I missed that day and then took the pills at very different times for the few days (4-5). Now, in the middle of my pack and toward the end of that week, I'm having light bleeding and very bad cramping. In the previous month, I had no cramping at all. This time it is very bad. I don't have an appetite and I have felt very sick. Even after I take ibuprofen, the pain does not stop and that is unusual. My period should not be for another week and a half or so. I am kinda worried that I am pregnant, but I don't know if it's probable or if I am just worrying about something that is completely normal....???