I don't have it but have heard that people who have fibromyagia have bodies that don't process Vitamin D very well. Apparently high than normal doses can help, and one article here says it has to be Vitamin D3.

http://healthandsurvival.com/2007/12/10/72/

http://www.ncbi.nlm.nih.gov/pubmed/16850115

My doc has me on 2000 MG per day.