My son is 4 years old he keeps complaining his stomach hurts what could it be ?

Abdominal pains: The list of causes for a stomach pain is very long. It ranges from the most benign constipation to the most concerning appendicitis to the more common food intolerance. Fist consider what else is happening and then have you child examined by your doctor. If there is no other complaints, you my want to wait a day or two to see if the pain resolves itself.

See below: The potential causes of abdominal pain in a 4 yo are huge, however, the most common non-life threatening reasons, especially if the pain is intermittent, are constipation, functional abdominal pain, GI viral infections, urinary tract infections, general viral illnesses, pneumonia with referred pain to abdomen. Severe causes can be: trauma, appendicitis, intussusception, mail rotation, etc.