The pain on the left side of the left breast may be caused by coronary heart disease, chronic gastritis and other diseases. 1. Coronary heart disease: coronary heart disease is caused by coronary artery occlusion or coronary artery stenosis caused by myocardial ischemia, often induced by exertion, emotional stress, cold, during the onset of the patient’s left side of the chest pain, accompanied by tightness in the chest, palpitations and other discomforts. 2. Chronic gastritis: Chronic gastritis will cause dull pain, burning pain, abdominal distension, nausea, loss of appetite and other symptoms in the upper and middle abdomen. Often accompanied by obvious time rhythmic, and closely related to diet. At the same time, pain in the lower three fingers of the left breast may be associated with breast disease, herpes zoster, intercostal neuritis, and lung disease, and needs to be carefully differentiated. It is recommended that when pain is found in the area of the lower three fingers of the left breast, it is recommended to consult a doctor in time and standardize the treatment under the guidance of a doctor after a clear diagnosis.