Hi Lisa and welcome. When I was looking for a new rheumy I called and asked to speak to his nurse and asked her questions on what his beliefs were on fibro, receptionist really can't answer questions like that since they don't work closely with the doc like the nurses do. Once I was satisfied that he treated fibro and myofascia pain syndrome I had to get a referral from my GP to see him. If you know others with fibro you can ask them about the docs they go to.
Yes some with fibro have low D and B12, my B12 is okay but my D is low. My rheumy also checked my magnesium and it was okay. Read the fibro 101 thread, second on first page, it contains a list of fibro symptoms that you can print off and check the symptoms you have to take to your doc. It also contains a list of "what else could it be" that needs to be eliminated before a fibro dx is given, fibro can mimic these. After all my testing was done and everything else had been eliminated I just happened to be in a flare when I went to my GP and he did the tenderpoint test and gave me the dx and then I went to a rheumy to confirm it. Thankfully my GP believes 100% in fibro cause I didn't know much about it when I was dxd.
Read and ask questions and we will be here for you.
luv and hugs
Marlee