She's seen an orthopaedic surgeon but he found very little. He concluded this was a an ilio-tibial band.
Although worse in the morning, she doesn't have pain in all directions of movement, making it unlikley to be arthritis (by definition). There is no clinically obvious redness or swelling or tenderness. If she externally rotates the hip (sits cross-legged) the joint is comfortable. Flexion and internal rotation cause pain. I presume this means that when the joint capsule is relaxed it is better.
X-rays taken last year, were normal. I'm puzzled because her symptoms seem to be deteriorating. Guess an MRI scan may shed further light and I'll ask her orthopaedic surgeon to see her again. My main purpose in asking was if there was anything obvious I'm missing.
Best to you,