Vitamin D Toxicity
Turns out Vitamin D has a very long (6 +/- month) half life and does not pee out like water soluble vitamins do. Toxicity causes fatigue and brain fog! My GP, the internet, and a simple, inexpensive blood test told me so. Iām waiting, like a lump on my recliner, for my blood levels to get back down into the normal range. Hopefully that will help me function a bit better.

Thanks a lot for highlighting this. I had heard that one never manages to get into the higher levels of vitamin d (in fact I took super high doses for 9 months with no change in my deficiency levels). So I supplement like crazy and now that I reached normal levels I continued with that, based on the math that I would anyway never get there. Your post was very helpful for me to stick to normal amounts now. Thanks! Hope yours goes down soon and so do the side effects!! ššš