How long does it take for vitamin d supplements to work? my vitamin d was a 8 and now its a 39. i still feel bad, brain fog and some pressure behind the eyes. my fatigued has went down and my bones stopped hurting?

First, can we be sure that your symptoms were due to inadequate Vit D levels as, in my experience, low levels were usually not associated with many symptoms. When your level reached 30 I would expect any symptoms caused by low levels to be reversed but this is difficult to prove.

Doubt that the described symptoms remaining are related to prior vitamin D deficiency, and now it is time for your doctor to reinvestigate the entire situation to uncover what else is causing your issues.