Everyone's body is different, but when I detox myself, I find what works best is ensuring to eat a big meal the night before while I'm still drinking. If I don't, then the withdrawals tend to be quite bad, and I can't keep food down either. I also find these multi-vitamin fruit juice drinks tend to work quite good as well.
It's simply your body releasing toxins. You've poisoned your body with drinking, and when you stop drinking, it will begin to clean itself. Your body doesn't want anything new in its system -- quite the opposite, it wants to get rid of the toxins. Do what you can to eat healthy though, and eat as much as you can, even more than you normally do if possible. One of the main causes of DTs is poor diet and an empty stomach, which is pretty common amongst alcoholics.