Be very, very careful with Vitamin D, it caused me to become worse, and apparently it has had the same effect, causing at least a few others to crash horribly.
I took a large dose last summer, and, quite unexpectedly, it basically nearly killed me. I had been suffering with PFS for a while, the it quickly caused me to crash and become much worse. It was a horrible mistake. Fatigue and muscle wasting only become a problem after that.
If you do try out this or other vitamins that potentially affect hormones, it might be best to try a very low dose out (below the daily dose), then wait a few days, try it again, and repeat this a few times for while. I’d try to avoid any large megadoses like that.