A child’s crying at breastfeeding may be caused by improper feeding, or it may be caused by diseases such as mouth ulcers, breast milk or milk powder allergy. 1. Improper feeding: If the position or bottle used by the parents when feeding the child causes the child to be uncomfortable, it may cause the child to cry when he/she is fed. 2. Mouth ulcers: The cause of mouth ulcers is not yet clear, and it is considered to be caused by a variety of factors such as genetics, diet and immunity. The child will have symptoms such as redness, swelling and pain in the mouth, as well as irritability, low-grade fever and headache, which will cause the child to cry whenever he/she is fed. 3. Breastmilk or milk powder allergy: If the child is allergic to breastmilk or milk powder, allergy symptoms may appear after drinking milk, and the child will cry when he/she is in discomfort. There may be other reasons why a child cries when he eats milk, so it is recommended to go to the hospital in time, complete the examination to clarify the cause of the disease, and then give targeted treatment or therapy under the guidance of the doctor.