Cramps: After Two Weeks?

Lately I've had some cramping in my right side, but basically my whole uterus. At the beginning of my period, i cramped so bad i was puking in school and i passed out a lot. This lasted five days, then subsided the last three days of my period. Then this happened. Its been 17 days since it started (25 days after my period). Its quite mild and comes in waves; some more severe than others. Im only 16 and have never done sex in my life. Im also unable to go to the doctor because my mom thinks im just trying to find something wrong with me. (In fact, when i told her of this, she thought i was trying to fake appendicitis).