I too suffered from Fibromyalgia - long ago, after a spinal operation. It was when there wasn't all this easy access to vitamins and magnesium. My specialist recommended magnesium and other stuff which I can't remember now, he used to make up a concoction for me in powdered form. In my view magnesium works a treat for aching joints.
I live on acres and we have cattle - just to be clear, I am not comparing anyone here to cows however, we had one that was down for the count (unable to stand up) and we were encouraged to give her a combination of magnesium and arnica tablets (extremely tiny little things) - we would mix it in with molasses and Lucerne - along with an injection from the vet (which we administered) she came good. Animals know when you are helping them and reward you in return. Paddocks in the winter down here shut down as it is too cold for any growth and nutrition is locked out hence we need to be mindful with salt licks and hay and or Lucerne (for special occasions).
Just like us if you don't get the right nutrients you run out of energy.
Side tracked I know but anyhow wanted to say magnesium, I think, works a treat
Take care