I was at 5k/day of D3. My cardiologist said that dosage might cause kidney stones. I began researching that tonight and found "
Vitamin D Intake and the Risk of Incident Kidney Stones" in the Journal of Urology, February 2017, by Pietro Manuel Ferraro, Eric N. Taylor, and Gary C. Curhan. It doesn't look like D3 up to 1,000 has much effect on kidney stones. But the authors didn't check high dosages of 5k to 10k.
10000IU D3 along with 500 mg K2 and 500 mg magnesium gluconate AND avoid consuming fructose as it subverts the process of converting blood D25 to the active form.