Hi, I am 36 , I have had ovarian cysts in the past . Now I have uterine fibroids , very small ones. Also very heavy menstrual bleeding on day 2 and 3 with huge clots on day 3. On a scan , I was told I have a thick endometrial lining, about 18 mm on day 8 of my periods.. What is the cause of this thickening. I have had regular periods in the past 8-9 years. With no pain. What can I do to have lighter periods.