shoulder tendonitis – HELP!!!!!!!

I have had a problem with tendonitis in my right shoulder off and on for many!!! years.
It has now reached a point where I have constant irritation. I do have impingement in raising my arm and reaching behind. I had an MRI so I know I do not have a rotator cuff tear, just chronic tendonitis.
I am taking mobic 7.5 for inflamation. I tried physical therapy but it doesn’t take long before I have a set-back. My questions are: is there a brace that would help my condition and could this all be related to poor posture.
Is there a brace to improve posture? HELP!!!!