When a three-month-old baby cries when eating milk, the following situations should be taken into consideration: First, we should carefully observe whether there is thrush, herpes or mouth ulcers in the mouth, if there is pain when eating milk, he or she will cry. Second, pay attention to whether there is a milk protein allergy, if eating breast milk is related to the mother’s diet, the baby may cry if there is a food allergy and is not comfortable after eating milk. Third, pay attention to whether the baby is sick, especially if the gastrointestinal tract virus or bacterial infection causes reduced appetite, poor digestion and reluctance to eat milk, of course, they will cry when eating milk. Fourthly, crying after breastfeeding may be a result of having had enough milk or feeling abnormal about the taste of milk, bloating or abdominal pain.