Has there been any x ray/MRI of the lower spine ,, just to check it?

maybe a position during surgery pinched something?
but then there would most likely be some pain..

So it doesn't hurt or anything ,, just that you can't move it?

I would hope they at least give you some therapy for it, maybe E stim?

I don't think any of the TOS group has ever had something like this happen.
If anything we do tend to slowly get more stiffness all over, I think it is due to adhesions and sticky tissues.
Or maybe a type of chronic myofasical syndrome.

Hope you can get it figured out soon ,, let us know.