Tooth ache !!

Question: How can one tiny tooth cause so much pain?? It even hurts when I drink water!! I don't know the source of the problem but have an emergency appointment for 7:00 tomorrow morning. I don't drink sodas; I rarely have candy or sweet deserts. I hoped and prayed (with my healthy eating habits) I would never get more cavities (and need more fillings)!! ~~ Imagine the pain as I attempt to eat my large green salad--my large salad with olive oil and vinegar dressing!!