No. No vitamins have been proven to work on hair regrowth. You should make sure your diet provides you with necessary vitamins. Especially make sure zinc and biotin are bountiful in your diet. They seem to be the ones your hair relies on.
Try biotin. Over the counter biotin can be helpful. Consider an examination with your primary care doctor to rule out other medical issues leading to hair loss.
I am recovering from anorexia, besides increasing my food intake, what vitamins can I take to stop the hair loss and help it grow back?
Anorexia, Depression. I commend you for working to recover from Anorexia. I understand your desire to have your hair grow back. See the Physician for Thyroid problem, Anemia and Diet Daily multivitamin containing zinc, vitamin B, Folate, (folic acid) iron, and calcium could be helpful. Accept yourself, who you are, Respect yourself for achievements of your life. See a psychiatrist for Therapy for stresses of relationships conflicts.
Should I take multi-vitamin tablets while using neutrogena for sebhorreic dermatitis to re-grow hair loss?
Sure. Multivitamin won't hurt. It's the biotin that helps nails/hair. If your hair loss is from seb derm only, treating the fungus w prescription shampoos will be the solution to hair regrowth, which is about 1 mm/mo.
Your choice. Most people who take multivitamins probably derive no benefit from them, especially if their diet and sun exposure are normal. There is no reason you cannot take a cheap vitamin-and-mineral tablet from a reputable pharmacy chain. Don't spend much money on them, and good luck with the continued treatment of scalp dermatitis -- it can take persistence to treat successfully.