Hidden pain under the left side of the clavicle usually has the following factors: first, common bone surgery diseases, at this time there can be neck and shoulder joint pain, frozen shoulder, claviculitis, costochondritis, osteoarthritis, can lead to the left side of the left under the clavicle of hidden pain. Second, diseases of the chest wall, common intercostal neuralgia or shingles, etc., can also cause vague pain below the left clavicle. Third, common circulatory diseases, there can be acute coronary syndrome, coronary artery disease, unstable angina, myocarditis, pericarditis, endocarditis and other infections, can lead to left subclavian pain. Fourth, diseases of the lungs, there can be pleural effusion, pneumonia, bronchitis, pulmonary tuberculosis, lung tumors, can lead to vague pain below the left clavicle. Fifth, women’s mastitis, breast lobular hyperplasia, breast tumors can also lead to vague pain under the left clavicle.