my TOS actually caused my scapula winging believe it or not! The muscles are all so taunt it's pulled the entire shoulder forward by 3 or 4 inches! NO matter how much I try to "hold it back" and do my correct posture positions it won't "stay". My stretches actually aggravate it
I thought I was seeing things when I noticed it and only casually mentioned it to the TOS dr and he confirmed it. So your winging scapula may be a symptom of TOS and not necc the cause.
Hope you get the answers you seek.