I am 18 years old and have not had a period since I first got it when I was 12 years old. This is really beginning to concern me and lately I ve been getting bad abdominal cramps but still have not gotten my period. I am a swimmer, but I am not extremely thin and I have a good amount of body fat. I am heading off to college this year and thinking ahead, this is something I would like to get dealt with. Would could possibly be causing this? What should I do about it? How do I treat these cramps with no actual menstruation happening?