I Am Scheduled For A Hysterectomy In 3 Weeks. My

I am scheduled for a hysterectomy in 3 weeks. My period will not end. Its pretty heavy and so painful despite being on birth control. The pain get excruciating at times.. debilitating. What can I do to stop the pain. Medicine does not seem to help the big pain waves and the big pain isnt constant, while tolerable pain is.