emergency contraception
"Ladies, let me tell you this pill works! 
My boyfriend and I had the condom fail right during the middle of my cycle. I went to the pharmacy about 9 hours later and bought some. Right after I took it I felt fatigued the whole first day. I did experience some other side effects as well seeing as I have never been on any hormonal contraceptive. I had cramps for the full two weeks until I got my period as well as breast tenderness. 
The week after I took the pill I felt nauseous, had sore breasts, sore back, cramps, and headaches. I thought I was pregnant and got really stressed out. 
I got my period right on time though despite my stress. My best advice is to just relax and wait it out. Easier said than done I know!"