I tend to go to sleep on my belly, but at the same time I have to be propped up, so my back is put under a lot of stress. I am a typical female and carry stress along my shoulders and neck, but my lower back is a fight I have had since I was 11 and broke my tail bone...do not do this..lol...it really hurts and will haunt you.
I think with the problems that fibro can cause muscle issues, in all parts of the body, is something that we need to know that we will have to learn to deal with.
Make sure that it is not your kidneys though. Cranberry juice will flush them out, but if it is muscular, then heat and ice alternately, along with, if you can tolerate it, ibuprofen will help relax the muscles a little and provide some relief.
"Life is not measured by the breaths we take, but by the moments that take our breath away."