If your breasts have been sucked once and keep aching, it is mainly considered to be related to external damage, infection and milk stagnation. 1. External damage: Sucking hard on the breast, or sucking for a long time, may cause some damage to the breast, and then the symptoms of pain. 2. Infection: If the sucking is not cleaned in time, or if the sucker has oral infection, it can lead to germs infection in the breast, which may cause localized hidden pain, paroxysm, redness and swelling. 3. Milk stagnation: When breastfeeding, women do not empty the milk, which can lead to milk stagnation and blockage of the milk ducts, which can also lead to breast tenderness. In addition, this symptom may also be related to intercostal neuralgia, pleurisy and other diseases. Patients are advised to seek medical examination as soon as possible to clarify the cause of the disease and follow the doctor’s instructions for treatment.