Well that's probably not good ....

I haven't slept well for two nights in a row, so ended up sleeping late this morning.

I'm not quite certain if it happened as I woke up, or I woke up because it happened, but I woke up to something going 'pop!' in the lower half of my pelvis, and a distinct sensation of something shifting rearward. Not certain if it was the SI-joint or the coccyx, but I think something definitely subluxed (or possibly un-subluxed). SI-joint is more normally a diagonal sliding sensation, this was definitely a front-to-back sensation, so it's either a whole new way for the SI to misbehave, or it's the coccyx.

It's also disconcerting to wake up to!

I now have mild pain radiating into the left buttock and thigh, worse on standing, so something's definitely tweaked the sciatic nerve.

Oh, joy!