Stomach pain can be caused by several diferent things. Most likely it is from something that was eaten that caused the pain. Most fatty foods can cause stomach pain, because of the content of fat in the food. Sugary foods ussually cause stomach pain. These types o pain usually goes away ater it settles in the stomach.
One possible reason is food. If your body is having problems digesting something, it could cause bad stomach cramps. It could also be your appendix--so talk to your doctor!