Since i do not know you age. I can advice you to do the following. There are various reason for shoulder pain with left arm pain and shortness of breathe.
commonest one is weakness (Anemia), it could be heart related that need to be confirmed by doing ECG / EKG, improper posture, acidity, calcium deficiency other.
Kindly me a physician to rule out all the causes and find the correct diagnosis and treatment.
Doctors Team Modasta.
Disclaimer: The medical information in this answer is provided as a source of information only. Please consult your health care provider before making any healthcare related decisions or for guidance about your specific medical condition.