Heavy menstrual flow is called menorrhagia. It is a common problem that always needs to be worked up by a qualified physician. The short list of common causes of this problem are 1. blood clotting disorders
, 2. Uterine fibroids, 3. Endometriosis. Blood clotting problems can cause your bleeding to continue beyond when it should. Uterine fibroids are benign tumors of the uterus (not cancerous) that can bleed excessively during a period. Finally, endometriosis is when the inner lining of the uterus grows abnormally outside of the uterus (such as in the fallopian tubes). This can cause excessive bleeding, horrible cramping, and trouble getting pregnant.
Cranberry juice is a home remedy that can sometimes help with simple urinary tract infections, but will not have any effect on your menstrual bleeding or cramping.
I suggest that you schedule an appointment with your OBGYN. He or she will want to know more details about how heavy your menstrual flow is (i.e number of pads or tampons over a certain number of days). You will need your blood counts taken to make sure that you are not developing anemia from the excessive bleeding. You will need a blood clotting test to make sure your blood is clotting normally, Finally, your doctor
will probably want to get a pelvic ultrasound
to look for abnormalities in your uterus (such as fibroids and endometriosis) which could be causing the bleeding and pain. Good luck.