Sorry to hear you are having so much trouble with your shoulder. Its just not much fun.
I have impingment and arthritis in my right shoulder due to a fall off of our motorcycle in the early 90's. I also was being seen by a neurologist for neck and low back pain. We really thought all this shoulder pain was coming from the neck, but then I started losing use of my right arm because the pain became excruiating. I drove a standard shift jeep and got to where I was not able to shift the gears, so had to find me an automatic to drive. I couldn't hold a hair dryer or curling iron in my hand, just nothing. So, finally the he referred me to an ortho to see if it could be the shoulder. I had forgotten all about the fall from the motorcycle.
I go see this cat one morning at 7:30 AM, he specilaized in shoulders. We discussed the problems with the shoulder and he said there was alot of inflammation going. He recommended injecting the shoulder joint, I said ok. Big mistake. He went down thru the top of the joint and hit scar tissue immediately. I nearly came undone, tried jerking to get away from him, screaming at him to stop that I was done. That was the one of the most painful experiences of my life and never again would I ever do it. I did not get any relief and for about two weeks the pain became worse, as if he had aggravated things.I have had my knees done and more needles stuck in me than a pin cushion so, I am familiar with pain. I went back to my neuro and told him what happened and let him know real quick, I had no intentions on returning back to that guy. I ended up doing trigger point injections which were much more tolerable because theu do not go so deep. I am not telling you this to scare you. My neuro said he should have numbed my shoulder prior to the injection and he didn't. Be sure the dr numbs your shoulder.
Alot of times they are able to scope the shoulder and go in and clean it up on the inside. That a much easier surgery than an open procedure. I hope the shots help and give you some relief. Take care.