Are your shoulder issues something you've pursued to the point of speaking with an orthopaedic surgeon to see if it's something that needs to be fixed to alleviate your pain once and for all?
I had a full thickness supraspinatus tear (part of the rotator cuff) about 6 or 8 years ago that led to almost constant pain that was inescapable. Cortisone shots would have me in blissful remission for 6-8 weeks, but that was only a solution a few times.
Eventually, I had reconstructive surgery on the shoulder. It SUCKED. And I say that as someone who also has a C1-C2 spinal fusion. I'd rather have another spinal fusion vs another shoulder surgery, which is why I'm so protective of my *other* shoulder now as it has suffered a few minor tears but nothing that hasn't healed thankfully. The surgery was painful and the recovery was painful. My ortho doc said that shoulders are one of the most painful surgeries and he wasn't kidding.
But, as much as it sucked, if I was back at square one again, I'd do it again. Because I'm now pain free. Well, in my shoulder at least, now other bits and pieces are acting up, but that's another story.
So, if it's at that point where it's causing you quality of life issues, riding and or otherwise, look into whether or not it's something that needs surgical intervention. If it's not as serious as what I had, the surgery is much less invasive and has a faster recovery, but rotator cuff injuries are in many cases not injuries that will ever heal, they need to be repaired.
And also ergos matter, as many have touched on. I have owned bikes where the ergos just never worked for me and I didn't keep them long. Honestly, my last bike, my Vulcan Voyager was right on the fringe of being one of those bikes where the ergos never fit me well. My new bike is just so much better in that regard. So as much as it sucks, when it comes to this sort of thing, at some point if you can't fix it any other way, one needs to face the reality that "this might not be the right bike for me".
And lastly...meds, yeah, meds. Don't be afraid of good old fashioned pain killer like Tylenol/Acetaminophen and anti inflammatories (NSAID's) like Advil/Ibuprofen. You can take both together as they work on different pathways and do not interact, just watch your maximum dosages, and try to avoid constant long term NSAID use as it can create stomach issues. But in the end, if all it takes is 2 or 3 pills to make you comfortable again, it's the simplest solution, yet it seems a lot of people are reluctant to go this route sometimes. If the NSAID pathway works for you, ask your doctor for a prescription for Vimovo - it's a nice prescription strength anti inflammatory with a built in stomach buffer/protectant. I switched to it years ago and take it fairly regularly for chronic pain elsewhere and I've had zero stomach issues.
Find a better one. Many are wankers. The good ones are gold. The last one I used for shoulders took me from a frozen shoulder that hadn't moved in months to full function in months. Horrible, painful months but I told him I wasn't interested in the perpetual physio treadmill. That was many years ago. I can't speak highly enough about that guy.
EDIT:
As for the corbin, do they tell you the measurements for how far down and back you moved? I would ask them. Move the bars a similar distance and you should be back in the game.
Yep, not all physiotherapists are created equal. I've been to ones where they just hook you up to the TENS machine for 20 minutes, rub you a little (one guy even had his phone in one hand while doing that bit), and then send you on your way.
But the good ones, are gold indeed. I have an AWESOME guy who I credit to singlehandedly getting me through my shoulder surgery recovery all while completely avoiding frozen shoulder as well as regaining virtually 100% of my range of motion.
Be careful with Celebrex. That was the last of a series of NSAID`s I took daily for over a decade, I had a very physical job and couldn`t function without it. I began with Vioxx then Bextra, then Celebrex. I`m certain they are responsible for my endless stomach issues.
See my comment above about Vimovo. Or even just get a separate script for an acid reducer and stomach buffer if you take a lot of NSAID's regularly. There are solutions.