If she gets the shot and it works post back. That sounds exactly like my hip.
I went for 2 years to a orthopedic center. At first they thought it was bursitis . Hip.
I had 4 shots over 2 years, 1 shot worked great, the others did nothing. They never used ultra sound for exact location.
Next they thought it was a nerve in my back, so I had an MRI, and they said I had spinal stenosis.
Back surgeon would not do surgery because he said it was not bad enough.
Next doctor they sent me to was a pain doctor. I had 1  pair of injections of the cortisone on the vertebrae 3 different times over 2 year
No help. Finally I went to another back surgeon  and she said my MRI showed my spinal joint was not bad enough to operate.
She sent me to another doctor who did all the bending you described, and he said it was a hip joint ( I think he said the sacro-illiac joint) and there was nothing they could do but live with it. My hip has been getting worse over many years/ decades. My problem is walking uphill or steps, then my hip gets really sore. Harvest season climbing the bin stairs and up and down the tractor combine steps kills my hip.
Driving distances makes getting out and walking hard to walk at first. Then it loosens up after many steps.
I am trying to lose weight, which should help a lot. They make a belt/like strap that you can wear that looks like those back belts only this belt fits over your hip bones. I have had  some relief but have not wore it lately. It is made for the sacroiliac joint. If that shot works I may go back to my doctors and consider a shot exactly in the s/i joint. I am not currently in to much pain.