If you're dealing with any kind of injury or longer term damage, conventional wisdom about things like bike fit go out the window. You're an experiment of one; you have to figure out what works and what doesn't for you. I've heard of fitters who do medical fits, but don't have any experience with one; it sounds plausible.
If I'd have listened to the cycling experts, I would have quit cycling 30 years ago - following the advice for bike fit and strengthening exercises would put me in excruciating pain for a week.
An example is saddle height. Mine is now at the low extreme in terms of acceptable angle at the knee. This eliminates all hip rocking; hip rocking is extremely aggravating to my particular back injury. Related, my bar drop is zero or even negative. On this setup, I've ridden 250 mile days, free of back pain. It's taken me years, decades even, to figure out what works and what doesn't. In term of bike fit, exercising, moving vs sitting, things to avoid, things to do more. When I started this back pain journey, I couldn't even ride 20 miles without aggravating my back for a week. The thing about my back pain was, during the event I'd be fine. 24 hours later, the pain would ramp up, eventually putting me immobile on the floor. But that's my spine, not yours.