Advice about pain around right ovary?

I'm 60 and on ne replacement therapy that consists of low dose estrogen patches and a l ring. I use porgesteron supositories monthly to induce bleeding and avoid build up in my uterus. For the past 4 or 5 months I have experienced intermittent sharp pain around my right ovary during the time that I am bleeding. The pain comes for approximately 2 hours ususally 2-4 times over a 3 or 4 day period. The first time it happened I went to the emergency room because I thought I might have appendecitis. So far the doctors can't find the cause of the problem. I've had a l ultrasound and the ovary looks fine. I would simply live with this, but when the pain does come it is severe and I can't sleep or if it is during the day, I need to lay down. Any suggestions of other things I should as about?