I eventually couldn't take it anymore and decided to see a doctor. Before I could be given a referral to a neuro they did blood work. My blood work revealed I was vitamin D deficient. Unfortunately Dr. Google has been very unclear as to whether or not vitamin D deficiency can cause BFS. I am just very worried and anxious because I can't tell if I am seeing any improvement or not yet. My basic question is does anybody here know the relationship between low vit. d and BFS?