What a "grade 5 lumbopelvic mobilization"--what all the medical science people (online) were saying I needed to get done (like, I was at the point where I was watching talks from conferences on lumbar spine radiculopathy issues)--does is it takes the ilium and the sacrum in one's pelvis and separates them slightly, essentially stretching the sacroiliac joint a bit (which is hard to do and requires enough directed force to make it really hard to do to yourself... that joint "normally" barely moves at all: it is at best a shock absorber) and then allowing it to go back to a maybe-more-normal position in the case that they have accidentally gotten locked into a bad place and ended up with some tissue (or even a nerve) getting pinched. Physical therapists will also do this, but as far as I can tell--after starting to try to get an appointment with a new one at around the same time (but unable to get one for weeks out)--they are way more addicted to following only the pathologies that have actually been determined by the doctor who prescribed you to see them (as that's how they work: the doctor give a you a prescription).