mulegolf I had a shoulder problem for years, basically it was full of lesions, calcium and other floating crap that didn't belong. Nothing out of place but the tendon was pinching and fraying with very little pain free movement of my left arm (so bad I could barely lift a coffee jar at times).
Tried steroid injection, instant pain relief. Come spring, first round of golf, may as well not have bothered. Pain returned in a hurry, shoulder stopped working again, ended up needing a subachromial decompression.
Not trying to depress you, you probably already know steroids can be hit or miss, and the hits temporary. If I was in the same situation again I'd skip the steroids and go straight for the op.