The vague pain under the left clavicle usually has the following factors: First, diseases of common bone surgery, which at this time can include neck and shoulder joint pain, frozen shoulder, clavicle, costochondritis, and osteoarthritis, all of which can lead to vague pain under the left clavicle. Secondly, diseases of the chest wall, such as common intercostal neuralgia or herpes zoster, can also cause vague pain below the left clavicle. Third, common circulatory system diseases, which can include acute coronary syndrome, coronary artery disease, unstable angina, myocarditis, pericarditis, endocarditis and other infections, can cause vague pain under the left clavicle. Fourth, diseases of the lungs, which can include pleural effusion, pneumonia, bronchitis, pulmonary tuberculosis, and lung tumors, can lead to vague pain below the left clavicle. Fifth, mastitis, lobular hyperplasia of the breast and breast tumors in women can also lead to vague pain under the left clavicle.