@closer0043 You are correct about TOS causing breathing issues because of causing so much tension on the rib cage interfering with its motion. When ribs expand, it creates a vacuum that expands the lungs bringing the inhalation. Often TOS is worse on one side, and for me my left side is tighter. The left side of my ribs don’t move to expand as fully as the right which means the left lung does not move as much. I have had repeated left sided chest infections because the phlegm does not clear as well. I also have allergies and asthma that add to that problem increasing the phlegm.
I do stretch muscles in my neck and chest using objects to push against the skin to create a shearing force. I go by feel of where the tightness is and I hold the pressure and wait. I can feel when it loosens when fascia starts to slide, and after this, I am able to start clearing phlegm from my lungs. I use tools to be the hands of a massage therapist and the key is to hold the shearing pressure and wait for a change which could take 5 minutes. I use small balls, a Davinci tool. and various things like a question mark shaped wand that has rubber knobs on one end. I can lay on my back and use both arms to direct it using the weight of my arms to help. I can also lay on my side and roll against this to get a force on the pectoral muscles from the center of the chest outward. I will reposition this and change direction just going by feel. I get a push upward by using a tool against a doorway while I am standing and pushing my chest upwards against it. I hope your PT understands this self massage, and this is how MFR works. This is how you stretch the fascia without having to stretch your arms in ways that aggravate the TOS.
Have your PT show you how to do this and you have to stay off of the arteries and veins when applying pressure or a direct nerve compression such as in the arm pit. You can work on the hard traps and Lats. Webbing straps are useful for arm pulls if you secure it on one end and use body weight to lean against it. I find it useful to work the area right under the collar bone and pull downward with a tool like a ball. This will pull on the neck on the tight fascia that is gluing it together and up into the scalenes. I can also lay face down on top of balls positioned on my chest and abdominal muscles.
If you can do this MFR stretching now, that may help your surgeon if your tissues can be loosened. I did this prior to my spine surgery and that helped in being more supple for retraction during surgery. With your multiple surgeries, you have scar tissue that adds to tightness. Think of it as a connected net holding your body together. My PT can stretch on my neck and I feel the pull down my entire body to my ankles. TOS is like wearing a straight jacket,
You are like talking to a mirror sometimes. I have been self massaging with a hard rubber ball and a lacrosse ball for the past 5 years. I usually work the trap and lat areas, but I will now try to target below the clavicle. I know my right side is very droopy from all of the throwing. I also used to have 2 rubber balls duct taped together that I would lay on with the balls on each side of my thoracic spine. I would then lift my arms over my head one at a time to massage my upper back. That would give me a lot of relief.