[Coffee.]

I never had month long periods, but I had two week periods for like, three years of my life. It was horrible. But then I found the answer to all my problems: Birth control.

However, depending on how heavy, this may not be a hormonal issue. I would highly advise you seek medical attention. My mother had this happen to her because of rapid weight loss. I do not know your situation, and am not a doctor, so I can't diagnose you. But there are many reasons this can happen and I would highly recommend you see a professional.