I am 16 and not on birth control (although now I am going to go talk to my doctor and hopefully get put on the pill, just to be extra safe). Last month I had 8 teeth pulled about 4 days before my period and was put on tylenol 3 and penicillin, and because I could not eat solids, I lost about 10 pounds. My cycle has been very regular for at least a year now. Thank you tons for your help, I dont feel as worried anymore. I'll wait it out for another week then go see a doctor. Thanks again!