Dai, good luck with the nhs. Until just before xmas 2008 i had similar pain. I'd put up with it for around 16 months before i went to doctors.
I stretch most days and considered myself fairly flexible.
Was offered painkillers and that but it wasn't my style.
I was given an appointment with a physio. Well i got 1 1/4 hours of her time but not once did she touch me.
Most of it was looking and then printing out sheets of paper with exercise i should do. The last 10 minutes was trying to convince her that i was beyond doing these exercises cos of the pain. No good.
I'd never felt so underwhelmed and helpless in my life. She could offer nothing else beyond paperwork.
A week later i saw a massage woman. She clocked by the end that i had a raised hip and tried pushing my leg back up towards my hip.
She also told me it was work related and i'm lifting something daily with bad technique. (I had used a mark 1 freedom trolley until then.)
I felt 80% better afterwards and could walk pain free.
I swapped to using hosereel and van mount and within a couple of weeks i was back to normal.
Anyway, the moral of this tale is if you are going to see a physio, see your daughter.
Unless i just looked untouchable, you won't get any hands on help looking for the problem.