As others have said, getting a med appeal is rare.
For what it's worth, I went through a similar shoulder injury. Rested for a few months, then made some changes to my serve (more angled stance in order to force body to rotate rather than just rely on shoulder rotation), plus changed to softer racquet / strings. End result is that my serve is as effective as it was previously, and I've been pain free for a couple of years.
There is hope - good luck!