It's a fad now, for MDs to put patients onto vitamin D supplements (D3 being the easiest and such)... mainly because most people aren't out in the sun as much as the generations before.

I personally have issues with D3 and take it a day or two and then skip... I cannot take it like my MD insists... my system does not need it in that dosage, if it needs it at all (I am out 5-6 times a day with my dog in the backyard.

Do a test. Go off the D3, keep notes on your reactions. I would go a week off the D3. Then go back on it and make notes.

It might not be the D3 itself, but what oils they are packing it in/with etc. Try something from a health shoppe and pick the one with the least ingredients?

Yes, it can cause dizziness, btw, imo.