Hello,
From what you describe so far it almost sounds like possible Thoracic Outlet Syndrome {TOS}.
Do you do repetitive work or lots of desk work?

does your neck, upper back or shoulders hurt or feel tight often?

I had a choking feeling for quite awhile with my TOS - it was the SCM & scalene muscles in spasms and pulling up on the top rib and collarbone.
{ quick explanation}

You might like to visit our TOS forum and read some posts , be sure to check out the useful stickys above the main threads.
Here is the link to the TOS -
http://neurotalk.psychcentral.com/forum24.html