Hi and welcome! I was thought to have a prolapsed uterus as well a few years ago but a good radiologist straightened that out ASAP. I was also told I was tilted, WRONG again. Who knows what is going on down there.
As far as I am aware of, this issue is not a symptom of FM, but then again I wouldn't be surprised if one day it ended up on there. We FMers experience so many strange things.
We are just the freaks of nature I guess.