Further update on this:

I am still struggling with it. The left psoas may still be an issue as posterior chain work seems to inhibit it and the left femur feels like it is coming out of the acetabulum, and the only way to get it back in seems to be to stretch the left glute.

The most interesting development is that both my brothers have now developed the same thing. Both have previously dislocated the left patella, and we all demonstrate the same faulty stabilisation patterns, involving bearing down and inhaled breath holding, lumbar rounding, thoracic extension, extreme neck flexion/chin tucking, even when doing very low level stuff.

None of us can expand our rib cage effectively and instead seem to breathe into the lower stomach and tilt the rib cage back, effectively firing up our extensors with every breath. We all carry our rib cage anterior to our pelvis most of the time, except when stood still when we slump either onto one hip or into a sway back.

We all have pelvis rotated to the right, ribcage counter rotated to the left, right scapular abducted, left scapular adducted, what appears to be internal tibial torsion on the left side.

Also found my Mother must be the source as she has the exact same structural issues, except without the neurological issues. I would presume me and my brothers have magnified it by being gym goers who have been reinforcing these patterns by performing exercises in a faulty fashion for so long.

One thing that seemed to cure it all was that me and one of my brothers had our atlas adjusted, and for a week after we felt light and full of function, exercises felt totally different, then we regressed back bit by bit over the next couple of weeks.

Has anyone any ideas what it is or what to try next?