After all you've been through so far David, I hope that the source of this problem/pain gets diagnosed quickly as a result of the test/scan results, and that a cure or solution is found quickly too.
The fact that you ache more today after lying so long in an uncomfortable position for the scan makes it sound like it might also be skeleton/disc related.
You have also been a lot less active and mobile for a while and that in itself can affect one's joints/bones, so persevering with your physical therapy or having more may be one thing they might recommend.
There have been so many folk here with (non cancer realted) bone/back ache etc post surgery and/or RT that I think it should almost be added to the list of side effects to be expected.
It may of course just be the coincidence of age.
I can't imagine that my aches and pains are as bad as yours, but I (too) am now finding find that every little ache seems to be twice as bad and last twice as long. It also doesn't take seem to take very long now to get a "bad back" from sitting, standing or lying in certain positions. Yesterday cycling hurt my knee, today walking hurt my ankle, last Saturday standing still at a meeting for ten minutes hurt my lower back, the list is almost endless.
I was told years ago that my joints could be aching because of what I ate (things like cheese, red meat, chocolate, fruit juice, coffee, alcohol etc that make acids inside you that then inflame the joints) So I hope an interesting discussion will ensue here if they tell you that it's diet related and that there is a list of foods that you must now eat or avoid etc, or that you should perhaps try some food supplements.
Alf