I wouldn't be too concerned about a diagnosis of fibromyalgia. It is the opinion of some doctors that fibromyalgia is a catch-all phrase and a subject associated with much quackery.
This is not to discourage practicing whatever you find benefits your health or trying new things, but to be upset about being diagnosed with fibromyalgia is pretty much the same as being upset at someone telling you that you have oogiemaschmoogietosis or something just as silly.
I had a massage therapist who diagnosed me as having fibromyalgia. She did Swedish and deep-tissue massage, and while she was a good massage therapist, she wasn't a medical doctor. She said that the pain I experienced at various points in the massage was due to the fact that I suffered from fibromyalgia. Maybe. But it's just as likely that she was massaging pretty hard. I didn't complain, because, you know, sometimes it's painful until the muscles adjust. She just noticed me wincing, I guess. Or maybe she took me too seriously the time I joked about knowing without a doubt that I would never be able to handle torture as a political prisoner after experiencing her deep tissue massage?
Anyway, tell your friend not to worry and to do a little research on the net about the condition, from sources both pro and con, skeptical and believing.
Thinking back on it, I kinda miss the massage. It was better than the chiropratic treatments. With her massage, she could gently turn my neck and my spine would crack and adjust. My god that was a good feeling!
There was this other time, too, that this man did this adjustment without any cracking. He just went right in with his fingers and adjusted each of my vertebra. Talk about bliss. I laid there on the floor with a completely still mind. I thought, in that moment, if I died right now, it would be a very happy death. I wanted to stay like that forever.
