A good, complex B vitamin was great for me. And still doing the usual balanced daily supplement.
Yes, vitamins and staying hydrated is the most important thing. Try to eat something, eat as much as you can. Get some food on your stomach.
I personally take daily multi vitamin, fish oils, vitamin D.
You would also be amazed how much a little exercise will do for you. It really helps to get moving. The first 72 hrs does suck… bad. Only you know you, if you have any feelings of confusion. Definitely consult medical professionals.
I take a multi and B complex plus vit D. The B really seems to help with energy.