What is this sharp pain going up my arm?!
Question: What is this sharp pain going up my arm?
It is a pulled muscle, or you may possibly have some rotator cuff damage. Since this has been going on for days and only happens when you lift your arm, you can rule out heart attack. If it does not get any better soon I would certainly ask your doctor where to go from there.
Consult a doctor asap. Sharp arm pain without muscle aches can indicate blood pressure and heart trouble.