Pain in the left arm near the armpit may be related to cervical spondylosis, frozen shoulder, trauma and other causes. 1. Cervical spondylosis: when suffering from neurogenic cervical spondylosis, radiating pain in the arm may occur. 2. Frozen shoulder: Early pain in the shoulder joint, with the prolongation of the course of the disease, pain aggravation, pain expansion, can involve the upper arm. 3. Trauma: When the left arm near the armpit is hit and other trauma, it can cause localized swelling and pain. The left arm near the armpit pain may also be local myofasciitis, it is recommended to go to the regular hospital in a timely manner to clarify the cause of the disease, standardized treatment under the guidance of the doctor, so as to avoid delays in the condition of the body to bring adverse effects.