You have pain extending from the neck to the left shoulder and scapular region. This could possibly be due to - neck muscle strain/ spasm - shoulder muscle strain - pressure on nerves in neck (least likely) I would advise you to stop going to the gym at present. In the least you must stop doing upper body exercises. Consult an Orthopaedic surgeon who will examine you thoroughly and may advise Xrays of the neck an shoulder. You may need a short course of anti-inflammatory and muscle relaxant medicines. Physiotherapy may be started later depending on extent of pain relief.