Same exact problem!! I've been looking for an answer for years. My blood work indicates my B12 is in range. I'm told it is "some kind" of deficiency...but can't find a doctor that can tell me What it is. I will say that when they first started curling it was a time period in my life that I first started experiencing constant fatigue. I've been looking on the internet for years for a resolution. PLEASE post the answer if you ever find out. Thanks.