From the NIH: Recurrent abdominal pain in a healthy school-aged child can be lactose intolerance.
D000005:Abdomen; D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007787:Lactose Intolerance / Q000150:complications* / Q000175:diagnosis; D010146:Pain / Q000209:etiology*