Infertility, IVF and painful periods

I am 39 years old. My husband and I have been trying to have a baby for the last two years. Before trying IVF I had a laparoscopy. The doctor removed a small septum, a couple of small polyps and some (not much) endometriosis. We tried IVF a few months ago with disappointing results. Lately my periods are much heavier (even with blood clots) and much more painful then ever before (almost unbearable). My infertility doctor has told me that the pain due to the hormone stimulation that I have to go through in order to prepare for the IVF protocol. I am about to try it for a second time. Apart from the small septum, the polyps and the endometriosis (which according to my doctor were all corrected) both my husband and I came out OK in all tests that were done (semen, hormones, etc.). The doctor also said that I responded very well to stimulation and that there is no apparent reason for me not to get pregnant. Before doing IVF we tried everything available, even artificial insemination. I cannot express in words the emotional roller coaster that this has been. Has anyone gone through the same experience? Any explanation for the heavy, painful periods?