Tummy pain in 3-year-old babies may be caused by cold abdomen, gastroenteritis and intestinal obstruction. 1. Abdominal cold: Since the stomach of a 3-year-old baby is relatively fragile, if the baby consumes raw and cold food or catches a cold in the abdomen, he or she may have a tummy ache. 2. Gastroenteritis: Inflammatory damage to the gastrointestinal tract caused by bacterial, viral and parasitic infections can lead to tummy ache in 3-year-old babies, accompanied by diarrhea, nausea and vomiting. 3. Intestinal obstruction: the intestinal tube can not pass normally due to external factors, there will be a large amount of intestinal contents, gas gathered in the upper end of the obstruction, which will lead to the phenomenon of 3-year-old baby’s tummy ache, with abdominal distension, bowel movement reduction and other manifestations. When a 3-year-old baby has a tummy ache, it is recommended to go to a regular hospital in time to avoid delaying the condition.