What you are experiencing could be caused by TOS, but it also could be from cervical spine issues, or even pec minor syndrome. You need a differential diagnosis to determine which. It is also possible, unfortunately, to have TOS, pec minor and cervical syndrome each contributing to your symptoms. One of the reasons TOS is so difficult to diagnose is that its symptoms mimic so many other conditions (cervical radiculopathy, carpal or cubital tunnel syndrome, etc.).

What part of the country are you in? There may be a TOS specialist in your area; check the Drs. and PT sticky at the top of the forum. You might need a vascular surgeon to rule TOS in or out of your diagnosis.

Good luck with your SSI.