I hate to say this but you gotta be a real pain in the butt sometimes to your docs to get things done. FM and chronic pain in general is something that most docs don't know how to handle nevermind the people who have it. According to what I read, in the past doctors were never taught how to deal with chronic pain that was non-malignant or non-cancerous.
Only recently have doctors become more aware of those of us who live in constant chronic pain because we spoke up and made them give us the care we need.
It is tiring and a real fight sometimes but you have to speak up sometimes. The squeaky wheel and all.
Good luck with your MRI.