We actually just wrote an article on the effectiveness of cannabis for those who siffer with auto immune disorders such as fibromyalgia:
In a recent study by the National Pain Foundation 30% of patients reported using cannabis for pain, which is not surprising given that traditional pharma drugs often mask pain but often have numerous negative side effects including addiction.
In terms of what is best for fibromyalgia, I can speak from my own personal experience but everyone is very different with cannabis, and it is most often a trial and error experiment. What I can say is that many people, including myself swear that cannabis helps combat fibromyalgia.
My personal suggestion is to try a high CBD product during the day such as a tincture or high CBD vape pen. CBD is an anti inflammatory and for me this really seems to work. If pain is consistent, then a higher potency edible at night can help you sleep through the night. I always start at 5mg THC and then go up from there.
I have also found that diet has had a profound effect on fibromyalgia. I took out soy and gluten and the pain diminished. I also practice yoga regularly and take Vitamin B and Magnesium regularly.
Hope this helps!