@beefirefly , I’m sorry that you’ve been having such a torrid time. Hopefully this light at the end of the tunnel will continue to glow for you.
There’s a few videos here which might cover some of your concerns :-
As for lower back pain, I’d normally post details about some useful stretches which could relieve the pain. But, I’m hesitant because of your condition. If your GP gives you the OK, You’ll find lots of instruction on YouTube.