All I can say is that this past March I went to see my endocrinologist. I already have Graves disease and neuropathy and a bad back. She also put me on a high Dose of D3 and within 2/3 days the nerves went haywire. I have since blamed the D for my massive exacerbation, which finally abated immediately after stopping the D. I think the connection could be with the inability to metabolize the D rather than a direct toxicity. Just read up on Phase 1 and phase 2 detoxification in the liver.

Best of luck