In this age it most likely hormonal imbalance but to evaluate the cause you do ultrasound... Udya might need the hormonal support to stop the bleeding and regularising the cycle

Hello, Menorrhagia is the medical term for menstrual periods with abnormally heavy or prolonged bleeding. In a normal menstrual cycle, a balance between the hormones estrogen and progesterone regulates the buildup of the lining of the uterus (endometrium), which is shed during menstruation. If a hormone imbalance occurs, the endometrium develops in excess and eventually sheds by way of heavy menstrual bleeding.consult gynaecologist.