Ahem. I had this problem right after my colon was removed, by I spent so much time on my back that it took awhile for me to notice it. I had a "cystocele", or prolapsed vagina; that is, the connective tissue wall that holds the vagina up had deteriorated; the lapsing vagina meant the bladder was lapsing, too. My gynecologist said it was from childbirth (30 years earlier?!) and age; I had surgery to correct, and it helped. But I think someone accidently cut that connective tissue during surgery; I know the surgeon had a resident and an intern there, and I think the resident slipped. Of course the doctors would never admit that. But you might see your gynecologist. It took a year to get the surgery, and it worked. I was pretty miserable before that. Good luck!