I am currently on birth control pills and have not missed any doses. I had light bleeding and cramps on the first day that my period was due, and had protected sex with my partner that night. Since then I have had no further bleeding but the cramps have stayed. I usually have quite severe cramps when I have my period especially the first few days, but could this have been early pregnancy bleeding? How can I find out? Does having sex on your period stop your period for the rest of that cycle?