There seems to be some compression in or around the cauda equina, I found out by pure fluke. I noticed I got a lot worse with the MCAS after doing hip thrusts with weights and after anything else that bends the lower back. Decided to hold my lower back really rigidly straight for a few days and my health issues were practically gone, and have been since.

There seems to be a few case reports online of people with MCAS getting a full cure after spinal decompression surgery but I think they had tethered cord syndrome.

Not sure what the best long term solution will be, need to find out why those nerves get crushed when bending but scans thus far are inconclusive