Probable culprit is a degenerative compression fracture and partially-crushed L5 vertebra. (not *quite* to the extent pictured top-middle here, but almost; mine doesn't have that much compression at the maximal extent (approx 40%, nor does the edge stick back up) your host is apparently kind of a bad-ass (now, with independent verification!)
"you see this triangle? those are the muscles of your low back. they're so tight they showed up on the x-ray."
my therapy is to continue to stretch and strengthen the muscles, and thus, my lifting and yoga and the kettlebell swinging is the right course of attack, so the muscles stabilize and support the degenerative injury site - this is one of the ones my dad had surgery to repair a couple years ago, iirc.
So, that's one down, and one to go. stupid chin lumps.
 anyone who isn't cassandrasimplx who recognizes that gets a not-cookie.