Here is a link to an article my Dr. wrote about Vitamin D:

http://www.goodhormonehealth.com/VitaminD.pdf

I also took Vitamin D3 for twelve weeks, 50,000 IU to get my levels into the normal range once it was discovered that I was vey low. Now I take 1000 IU every night with calcium before bed.

I think it's great that your TSH levels are normal. This basically means that your thyroid gland is working well and that it's receiving the hormones it needs to work well from your pituitary gland, and that your pituitary gland is receiving hormones it needs from your hypothalamus which is monitoring the hormones secreted by your thyroid gland.

Did you ask your Dr. to test these levels for you? Did your Dr. order this testing because of your concussion/PCS symptoms?