Hi,
Your questions and some of your symptoms and the car accident that you had, make me want to suggest that you might want to read a bit on our Thoracic Outlet Syndrome forum.
The symptoms of TOS can be confused or overlap with C spine problems, not always of course, but the mention of your shoulder involvement and previous surgeries etc {scar tissue??} anyway I just wanted to mention TOS and post the link for you.
http://neurotalk.psychcentral.com/forum24.html
be sure to check out the useful sticky thread.