Many thanks again Dr Corenman
Yes, that matches what is happening. I do get mild aches in the glute and upper back of the thigh. I kinda ignore it most of the time as it is easily tolerable compared to the back pain. I could not say for sure re the SI joint but I have had pain on the bit of the hip/sacrum that protrudes slightly.
So on with the PT. I see the doctor again in 3 weeks. I will see about the injection again. Worst case, my surgeon left this option open when I saw her last 6 weeks ago. She was not keen at the but I got the sense she would not object after another couple of months.
Anyway, thanks so much again. I will do my best to update the thread as things change in case it helps others later.