What could this left arm pain from shoulder to hand be?

Several things. Pain that severe needs to be worked up by your doctor in person. He/she will listen to you, perform an examination and possibly order some tests to see what's wrong with you.

Related Questions

29/f. Left arm pain sometimes starting in shoulder down to hand and sometimes vice versa. Shooting\achy pain. Had EKG last week and came back good.

Nerve compression. Sounds like a compressive neuropathy of the upper extremity. I think an evaluation by an orthopedic surgeon is reasonable. Sounds like you need an EMG to find out where the nerve is compressed. Could be at the neck or a more peripheral site. An EMG would show that. Read more...
Pinched nerve? You might benefit from seeing a neurologist or a physiatrist to see if you have a pinched never from neck to the fingers. Ekg is not enough to see if you had a heart attack. Try getting a multifunction cardiogram to see if you have ischemic heart disease also. Read more...