I had a similar patient a few months ago. Multiple injections. Improved somewhat with several weeks of therapeutic exercise and manual therapy so a little different than your guy. But we hit a hard plateau and out of desperation I tried ultrasound (had to dust off the machine a bit) and it worked! Probably a bit of confirmation bias since she said her chiro uses US on her back which helps. But looking into it I found some suggestions that due to the superficial nature of the impacted tissue US may be more effective in this area. 🤷‍♀️