Fibro is a multi-faceted condition. When asked as to what causes it, the answer is just about EVERYTHING.
Poor bio-mechanics can lead to fibro, especially after a bad accident. It seems that the C-1 Atlas vertebrae plays a huge part into it. Fix the atlas and the nervous system comes back online. Also NCR (neurocranial restructuring) helps many sufferers, because when the skull (head) is on straight, the entire spine unwinds and the structure changes.
Doctor Brice E. Vickery wrote many articles about how all fibro patients seem to have the same spinal degeneration going on because of protein deficiency. He recommends a specialized amino acid formula called Platinum Plus amino acids. You can do a search on that and get several pages.
Dr. William Wong talks about ischemic pain of fibro and he says that fibrosis contributes to it. He wrote an article called "Fibrosis, The Enemy of Life. He recommends systemic enzymes to eat up fibrosis, excess fibrin in the blood, and they decrease systemic inflammation. The main enzyme is Serrapeptase.
Also low thyroid function plays a part in fibro. The low body temperature syndrome also known as Wilson's thyroid syndrome has the same symptoms as fibro, particularly the chronic fatigue part of it. Dr. Denis Wilson, MD seems to think that they're one in the same. Also another doctor name Dr. John Lowe recommends T3 (thyroid hormone) to relieve fibro. Which is basically what Dr Dennis Wilson recommends, the only difference being that Dr. Wilson recommends the timed release form made by a compounding pharmacy.
There is a foundation called The Keshe Foundation that has promising treatments and trials for fibro. They reason to treat the body as a galaxy in their trails. You will have to look that up and read the part under health. They also call it a body reset.
And sometimes vaccines can cause fibro, as admitted in their package inserts under adverse reactions. They call it just myalgia, but they admit it in the prescribing information. A detox would in order.
And sometimes, the body just need to detox and be fed certain nutrients to recover. Each individual is different.
Can find all this information in a google search or use the FC toolbar search. It's all there.