If you are only suffering these effects after a night of drinking, it doesn't sound like a food intolerance as much as it is an effect of being a lightweight. (Yeah, me too. Didn't used to be. Oh well.)

If it is just a hangover, it will help to drink water all night (2 glasses per one serving of alcohol is best, but many folks don't drink that much water). Sugar also tends to buffer the effects of a hangover -- which I don't really understand since sugar is also a dehydrating agent. Coffee is counter-productive, as it dehydrates the body further.