What Causes Pain & Heavy Bleeding During Menstruation?

My level of FSH was 92. I was told his is typical of a postmenopausal woman. My pelvic ultrasound showed an endometrial thickness of 6 millmeters. I had heavy bleeding for about 7-8 days and strong pain. I never felt this much pain before, never had this type of bleeding before even when I did get period it only lasted 3 days with no pain ever. i haven't had any bleeding since. I am due for a endometrial biopsy on July 6th, but after reading various infor. should I be concern? What does this mean and could the ultrasound show cancer? polps? what causes the thickness?