Hi! Vitamin d3 is converted by the body to a biochem compound called hydroxyd25. Make sure that the doctor ran a blood test for this instead of d3 sorry on ipad -- misspelled it. D-hydroxy 25. When you take vit d supplement, see if you can find it in the d hydroxy25 formulation versus d3 -- it is immediately bioavailable that way. PS serum d3 tests are ok -- but just not as informative as running hydroxy 25 test which will tell how your body uses the d3 it gets. I believe d3 is fat soluble so you want to limit, unless you have otherwise the need to take it, your lifetime intake of it.
I found out the hard way that high doses of vitamin D use up magnesium and I was already very magnesium deficient! And symptoms of magnesium deficiency include pain! I had vitamin D resistance as I was severely magnesium deficient and only when I corrected my magnesium deficiency was I able to raise my vitamin D and calcium levels.
It can take many months for vitamin D levels to rise (this is of course with all the co factors in good supply). Vitamin D has a number of cofactors and the most important are magnesium, vitamin K, zinc, boron and vitamin A. The Vitamin D council state optimal vitamin D [25(OH)D] levels should be between 50–80 ng/ml (125–200 nmol/L).
Are you taking just taking Vit D supplements, if so that may be part of the problem. Vitamin D for example should be taken with folic acid. I had that problem when I started vit d alone.