If you feel soreness and numbness from your left shoulder to your arm, the first thing to consider is frozen shoulder, as frozen shoulder can cause soreness and numbness in the shoulder area. When frozen shoulder is more serious, it will make the soreness and numbness radiate to the upper arm area. You should seek medical attention to determine the cause of the disease in order to treat it and avoid delays.
In addition, there may also be a cause of cervical spondylosis, and a cervical spine X-ray or magnetic resonance imaging (MRI) may be examined at the hospital to assist in the differential diagnosis.