I have been on birth control for years now and I have never experienced this while on birth control. I had unprotected sex with my husband on July 17th. I missed my birth control on July 16 and took two at midnight on the 17th (maybe even later). The pills I missed were at the very end of the 2nd week of the pack. I did get my period 2 weeks later but it was 2-3 days late and very light. I only went thruogh 1 tampon a day. And now on Aug 14 my left breast and nipple is tendor. The other is too a little but not much. I have been going pee more often too. and have been getting lots of headaches. Oh yeah and during my last peroid I got cramps and I never ever get any cramps during my period. What can this be?