Digestive upsets get us all at one time or another. Simple causes may be from a meal that didn't agree with us causing indigestion or some unwanted stresses that affect our lives from time to time. Mostly there is an excess in stomach acid that gives a bloated feeling.
More serious conditions such as ulcers, IBS, Chrons, etc may also occur & need medical testing to confirm any prolonged pain or discomfort.
In TCM terms this is described as Damp Heat in the Stomach or Stomach Fire, depending on the severity, along with other signs & symptoms.