Vitamin D3 makes me literally insane with anxiety. I've tested it dozens of times, each time with the exact same insane anxiety effect.

So, recently I tried D2, and no apparent negative reaction. You seem to even react to that.

On amazon.com you can get plant based D2 made from yeast and D2 made from mushrooms.

Yeast: https://smile.amazon.com/Amazon-Elements-Vitamin-Capsules-supply/dp/B01L081FN6/ref=sr_1_5?dchild=1&keywords=D2+vegan&qid=1592777867&sr=8-5

Mushrooms: https://smile.amazon.com/Mushroom-Supplements-Supplement-Vitamins-Softgels/dp/B07ZC7QXFN/ref=sr_1_3?dchild=1&keywords=mushroom+d2&qid=1592777884&sr=8-3

Perhaps one or the other might work for your body chemistry.

And if neither, then just get outside in the sun.