D3 deficiency.. i've had a severe D3 (my D2 is good) deficiency. (D2 is from the sun.. mine just doesnt convert well to D3, so getting more sun dont help in my case). I was on 2000mcg cholecalciferol per day (standard supplementation dose in Australia for those with D deficiency) but after several months or so.. my D3 levels were even worst. While at the hospital for something else, they gave me a dose of 50,000mcg to take in one go. Ive no idea how that went as i havent had my levels tested again (and my doctor threw my case in the too hard basic when the normal supplementation amounts failed, this was a couple of years back), so i then went back to just taking 2000mcg again as I know i would of gone quickly deficient again. i recently had a specialist do a heap of blood tests and asked for my D3 levels to be done too, so i'll find out soon just how bad they are (thou i've kept up continous supplementation). ...................... I also have to take Calicum too or otherwise my mood swings are worst. Vitamin D and Calicum work together in some way (i cant think how right now).