I'm having a period for 12 days and still counting. i don't know why but at my first day i didn't feel any cramps.

Long period: A longer period, with or without cramps can represent an anovulatory cycle, a spontaneous miscarriage or pregnancy if you are sexually active, or an infection. I would seek medical attention to determine the reason you are still bleeding.

DUB: You probably have what is know as dysfunctional uterine bleeding. This can be structural or hormonal. Continuous bleeding can lead to anemia and its complications