Hello Thanks for writing to us. It would seem that your breast tissue is very sensitive to hormones, including progesterone. If you have not tested your hormones during hormone therapy it’s not possible to know if they are in excess, or the breast tissue is just extra sensitive to normal levels of hormones, or both. However Vitamin D is also important for normal breast function, so this may also be an issue for you. You should check your Vitamin D level and consider supplementation if low. I think you should visit your doctor and ask for another substitute. Thanks Dr. Tripat Mehta