Hi there Alewife!!
Welcome to the greatest Forum known to Fibromyalgia kind!!!
I know in the past others have posted a question much like yours. So, you might want to go back and read some other posts on the topic.
I usually try to take a bath or shower before sex to help with my pains and to relax. Hubby and I have also learned that there are some positions that just don't work anymore because of my pain problems. I'm trying to be very delicate with what I'm saying.. LOL.. it's not easy.
Have you ever had any xrays or mri's of your back or pelvic region? You might have a bulging disk or some other problem. I have a lot of lower back problems and compounded with fibro, sex can be a slow go. There have been a couple of times that I could barely move for a few days after a sexual encounter, so, I try to go slow and I always have to keep it in the back of my mind,,, if I do certain things (trying not to be too graphic), it will bite me in the butt later.
Perhaps your problem isn't a gynocological one but an orthopedic one. I would definatly mention it to your doctor that treats you for fibro and see if he/she would want to get an xray or mri. There could be a host of other things going on.
Good luck... and again, welcome!!