Hi Dawn
Sorry to hear you are struggling with hip pain. Steroid injections do tend to have a limited lifespan although, from my own experience, this seems to vary considerably. A 'flare' generally involves several joints as it is the sudden onset of inflammation caused by over-activity of the immune system. Individual joints can be affected particularly when they have perhaps seen a period of over use.
I wonder whether it is actually the hip joint itself or rather inflammation of the bursa (bursitis) which lies over the joint. This can cause intense pain and does indeed feel as though it is the joint itself causing the problem. I have had a few periods of bursitis in my right hip and on the last occasion received a steroid injection via ultrasound directly into the bursa. This ensures the right area is treated, often difficult to acheive when a large area is involved. For me that did the trick and it must be 3/4 years ago now and I've had no further problems
Certainly worth getting in touch with rheumatology for advice and in the meantime perhaps some stronger pain relief might help. Hope things improve soon,
Lyn x