Stretching and exercising in PT made me worse (manual therapy and massage therapy helped). While I was able to improve my posture some, my TOS symptoms only got worse. Like you, my 1st rib simply would not move. I finally found a group of therapists that understood TOS and they analyzed my entire rib cage and found that the ribs below were all out of whack and pushing up on the 1st. That is when I decided to have rib-resection surgery. Once I had surgery, they found that my brachial plexus had fused to the first rib with scarring/adhesions.

Now that I have both 1st ribs removed, my ribs and thoracic spine have increased mobility and PT that was previously ineffective is now helping.