EVERY OTHER WEEK?!

Savanna
So I went out to college this year and ever since then I have been getting my period every other week. Get it on a Tuesday, last for four-five days, then skip a Tuesday, then get it again the third Tuesday. This has repeated for four months. At first I thought it was just stress, but I am totally adjusted and happy and feel comfortable with my lifestyle. I have not started any new medications or new foods. I'm not sexually active. I have no idea what it could be. I didn't want to go to the health center on campus, I'm going home for Christmas break and will probably make an appointment. Does anybody have any ideas as to what the cause could be though? My cramps have not been as bad as they normally are- instead of constant aching, I just get random shoots of pain. Also, my appetite has increased a TON but I've kept that under control. Thank goodness for the broke college student grocery budget- I still eat healthily though (such as yogurt, rice, veggies.)I have no idea! Please help!