I have a mild cold and I felt nauseaus all last night, except for when I was actually eating something. When I was sucking on a cough drop, chewing gum, or eating, I felt fine. When ever I get a cold this happens. Why? And this post nasal drip?

It's not exactly nauseaus in my stomach, it's in my throat. It not bad to the point of throwing up, just irritating enough to keep me up and night. What can I do about this?