Thankyou for your comments. I note that you eventually had both hips replaced. I have other health issues which will affect possible surgery decisions. The physiotherapist linked with the hospital has suspended any treatment until a new diagnosis is made. As I already have a combination of psoriatic arthritis and osteo it seems that nobody can decide which is where! I just seem to be in a whirlwind of tests,x rays,injections - and no real plan of attack. Very frustrating. I do understand that steroid shots used longterms are not a good idea - I feel the same.
Low back pain invariably changes the way your stand, sit, walk, etc. The constant strain as your body compensates for the pain inevitable causes the adjacent muscles to swell and press on sensitive peripheral nerves. This is probably what's causing the buttock pain - this is a hall mark of sciatic nerve irritation. Because all parts of our bodies are connected, the pain may eventually seem to spread to hips, knees, etc.
Have you been given gentle exercises to stretch and strengthen your back and abdominal muscles? Also, ice packs at the base of your spine may help decrease inflammation and ease some of the pain. I had this before my hips were replaced, when the hip pain was affecting my lower spine alignment.
A pain management clinic is an excellent idea. Long-term use of steroid shots isn't a good idea. Good luck!