The causes of vague pain above the left chest with hidden pain in the armpit include muscle injury, pneumothorax, brachial plexus nerve injury, etc. General treatment, exhaust treatment, medication and surgery can be used to eliminate the disease. 1. Muscle injury: overwork or strenuous exercise can easily lead to muscle strain above the chest and underarm, which in turn will produce pain. In this case, it is recommended to take more bed rest, do not engage in heavy labor, and if the pain is serious, it can be relieved by hot compresses and other means. 2. Pneumothorax: When gas accumulates in the pleural cavity, it may cause the pressure in the pleural cavity to rise, compressing the lung tissue and causing vague pain above the left chest with hidden pain in the armpit. For this problem, thoracentesis and closed chest drainage are often used to accelerate lung reopening and relieve pain symptoms. 3. Brachial plexus injury: Brachial plexus injury is mostly caused by external pulling and fracture. After the onset of the disease, it may lead to pain above the left chest and armpit, and even upper limb dysfunction in severe cases. For pain symptoms, medications such as meloxicam and celecoxib can be taken to relieve pain. It is also necessary to use methylcobalamin and vitamin B1 together to promote nerve recovery. In addition, according to the actual condition, the disease should be treated from the root cause through surgery, how to avoid the recurrence of pain symptoms. Commonly, there are nerve release surgery, nerve suture surgery, nerve transplantation and so on. There are other reasons for the vague pain above the left chest, you should go to the hospital in time, and follow the doctor’s instructions and active treatment. The above medications need to be used in a standardized manner under the guidance of a doctor.