Can you describe exactly where in your arm you are having the pain?
Does it travel into the forearm, or hand?
How old are you?
Do you have pain in your neck as well?
OK.
Do you also have symptoms that involve the thumb and index finger?
Is it worse if you move your neck, or tilt it to the side?
Well, it's good that you have had the serious (heart) issues ruled out here.
So, the pains you are having -- the ones that travel down the shoulder into the upper arm and forearm, seem to be more related to something like a "pinched" nerve.
Given that you are 22 years old, the heart as the cause of pain is even less likely.
So, this may be temporary inflammation of the nerve, suck as where it starts in the neck, causing your pains.
http://orthoinfo.aaos.org/topic.cfm?topic=A00332
You may feel better in a few weeks (most of the time, this inflammation improves on its own) or if not, may need further evaluation of this condition -- but it looks good that your previous studies and EKGs have ruled out the potentially serious causes of this pain.
Well, given your EKGs are normal, and your young age, and a CT that is normal -- it probably is OK.
Pains from "pinched" nerves can also cause pains that appear to be the top of the chest area.
Of course, continued followup with your doctors, should the pain not improve is important.
Doctor (MD)
U.S. Physician/Surgeon in Neurosurgery