Unfortunately, without knowing more specifics, I wouldn't be able to help pinpoint what might be wrong. However, I can give you some questions to ask yourself. 1. Is the pain severe? Is it so bad you want to double over and scream? 2. Is the pain recurrent? Has it been around for say, a day or more? 3. Do you have a fever? If so, is it a high fever or a low one? 4. Have you been under a lot of stress lately? 5. Does eating certain foods make the pain worse? Especially spicy foods and/or caffeinated ones? 6. Is the pain directly in your stomach? Does it move? Is it on the left or right side? 7. Did the pain start after eating excessively? Or after heavy drinking? 8. You mentioned that you don't have diarrhea, but are you constipated? 9. Is your stomach/abdomen area swollen or tender? 10. Any vomiting at all? There are so many diseases/conditions that occur around the digestive system and abdominal area. I don't want to freak you out, or scare you. It could be something completely harmless. For instance, I recently (very much accidentally) ate a tiny piece of raw tomato. Ugh. I'm rather allergic to them, so for the next few days my stomach was in agony. However, if you have any of the severe symptoms (vomiting, *high* fever, severe constipation) get medical aid as soon as possible. If you've been under a lot of stress lately, and/or the certain foods aggravate your symptoms, you may have the beginnings of an ulcer. If you don't have any of the above symptoms, sorry for taking up so much space. :D If you don't have any of the more severe symptoms above, I would suggest just coddling yourself for awhile. Get plenty of rest, non-carbonated/caffeinated liquids, and eat rather bland food. If your stomach pain gets worse, or lasts more than a few days, or leaves and returns, screw the bland food and all that. Get medical attention. However, (once again) do jot these symptoms down in a notebook, planner, scrap paper...whatever. That way, even if this isn't anything serious (as I'm sure we're all hoping!) you can ask someone about it later. You can ask what caused it, how to treat it, how to prevent it, etc. Anyway...good luck and I hope this helps :D

First of all, take nothing by mouth. No food, no over-the-counter medicines, no more water than required to moisten your mouth. If the pain persists (or has persisted) 24 hours, CALL YOUR DOCTOR. If you don't have a doctor, find one. Go to an emergency room if necessary. What you describe could be nothing, but could equally well be the onset of appendicitis (to take one obvious example) or any number of other things. DON'T risk your life on a diagnosis or advice obtained anonymously over the web.

Eat something, I get that way when I take my vitamins and don't eat enough

EDIT - My answer makes NO sense now it has been moved!!!