Why do my teeth hurt so bad?

I just had some fillings done on each side on the top mouth a week or so ago. Now every time I eat anything hot or cold my teeth hurt so bad and the pain doesn't go away until I take some tylenol or other pain reliever. They don't usually hurt until I eat something I have to chew. I had macaroni and cheese for breakfast and my teeth didn't hurt but I just ate some deep fried mushrooms and now they are killing me. What could the problem be?