Pain in the left shuolder has many causes to it-
Rotator cuff syndrome
that can either be a strain/sprain, or a tear.
Spasm of trapezius due to misuse/overuse.
Pain arising from cervical spine
often travels down shoulder into hand also.
Referred pain pain from stomach or other abdominal structures (ulcers, pancreatitis, or in the chest (myocardial infarction
[heart attack], pericarditis, pleuritis, pneumonia, pulmonary embolus, aortic dissection
).please visit a orthopedician for further evaluation.