Lefthookdad...
First of all I am sorry to hear about your boy, and I know how you feel because I have gone through the same thing and you wish it was you rather than your son. I am sure that all in the forum feel so bad to hear about this injury.
My son in the summer of 2013 (late August in East Cobb) in one game of the tournament while warming up, could not throw and his shoulder hurt. We shut him down and hoped for just an inflammation, we did the O'Brien's test and did not point to labrum and surrounding area.
The pain was there only when his motion was throwing, but at the end of the throw, not during the throw. We took him to an orthopedist and he thought he was inflamed and rest. This did not help and we ended up getting an MRI and discovered he had a
SLAP tear (Superior Labrum Anterior Posterior).
OK, now the original MD guy wanted to repair it by doing a arthroscopic debridement or cleaning-up of the tear in the labrum. This obviously was surgery and we really did not want it if at all possible...recoup time is 6-9 months.
Took my son to a 'baseball' sports medicine guy who treats college baseball players as well as an MLB team players. He did the standard tests, saw the MRI, told me that most baseball players (his words) soon or later have some kind of tear, and that most players he has seen have it. My son's slap is a type 1 which is a fraying with no detachment of the biceps from the glenoid socket (type 2 the biceps is separated from the glenoid). He did not recommend surgery and put my son through 24 therapy sessions (with a guy that knew what to do), and after all the hard therapy, he started his throwing program. The therapy cured him. Like the baseball dr said, and now all the surrounding muscles and tendons are now working in tandem together in the shoulder. So players can live with a tear if properly treated.
My son is at 100%, while he is not a pitcher (SS) his throwing is even stronger and throws 90 from the outfield, no pain whatsoever. He is even considered a prospect by MLB scouts. There is no pain in the shoulder; he continues his weight program and always does his therapy exercises before lifting in the gym. My son is a senior in HS and is going to a play at a fantastic school's D1 baseball program.
My point is...try to get a guy that knows 'baseball medicine', it may be that your son also has a type 1 and therapy 'will' bring him back. Get that second opinion and ask what about therapy. This is by no means an end. Also, a cortisone shot is only to reduce inflammation (thus the pain caused by it) but will basically not do anything to repair a slap tear.
Best to your son and hope he comes back soon.