pretty much what the last 4 people said
greasy food (home cooked if u can manage it) drink alot of fluid, if u got nausea drink a lil bit of tea made from dried mint and pieces of ginger (make sure its real ginger)
you can try distilled peppermint water, that helps with real bad headaches
but most of all, smoke a blunt, or if you can stomach it, eat a brownie thats way better for your digestive tract