Is Estring Advisable For Prolapsed Bladder?

I am 72 years old with a prolapsed bladder. My urologist wants me to use the estring, but the side-effects make me very nervous. I was told by my obgyn not to take premarin any longer since I had two findings on my mammogram. One needed a stereodactic biopsy and the finding was benign, the other was nothing. But, in the important drug information, it states that the estring can cause breast pain, breast lumps or nipple discharge. I react to medication and am very nervous about using this ring.