Level 1: What is diarrhea in four-month-old infants? Diarrhea refers to a digestive disease in which the number of bowel movements per day increases, the amount of stool increases, the stool is watery or semi-watery, and is accompanied by abdominal bloating, abdominal pain, nausea, vomiting and other symptoms. Diarrhea in infants aged four months is common in newborns and young children, mainly due to intestinal infection. Level 2: Four