Yes, vitamin D3 is good, so are the fatty acids (particularly Nordic Omega 3's, although there are many different ones available), vitamin C, the whole series of Vitamin B is very boosting for the nervous system. In fact, I would recommend a pharmaceutical quality multivitamin once daily.

It would be very helpful for you to see a psychiatrist just to determine if you have a chemical imbalance that needs to be stabilized. Being medicated for it--if it is there--could turn things around for you very quickly.

I agree that a psychiatrist could be of real help and you might wish to see one as soon as possible.