Severe pain in left arm stabbing and then dull last for about 2-3 hrs?

Must call the doctor: A person with left shoulder or left arm severe pain symptoms has to go to her doctor or the E.R. to be checked for a heart attack. That means not waiting at home to see what happens next. It could turn out to be a lung problem, a bone or muscle problem, a nerve problem, or an acid reflux problem, but the heart attack kills people. Better safe than sorry. Calling 911 for an ambulance the quick way.