In my experience, the only thing that made me feel better after kicking was time. it takes a little while to start feeling better. The good news is that off heroin, it doesn't take too long (at least for me), maybe a week or two to feel "normal" (methadone takes a shitload longer). Multi-vitamins are a great idea, healthy food too......for me though, chocloate was a miracle, I ate tones of candy bars, I think it has something to do with chocolate affecting some of the same receptors that dope does, but that's just a guess...
Good luck, it does get better!