In reply to john morrissey
Professional physio for sure to start with and initial diagnosis - but theraband usage for strengthening is good and stretching up wall as described above is good. Must keep moving - problem is that pain can be too great to do much. I was lucky enough to get a diagnosis on both shoulders from a really good shoulder doctor at Wittington (the shoulderdoc website is excellent).
I subsequently had an arthographic shoulder distension which involves saline and steroid injection to release the shoulder- all I can say is best solution I could have hoped for - I am back to full movement climbing normally - the treatment was 100% effective.
Mine came on quite suddenly after some heavy ditch digging where I stressed my shoulder joints - although the cause is not always known that sort of thing can bring it on. It's worth doing regular strengthening exercises to keep the shoulder strong and not becoming lazy again.
It's a nasty problem to have which is basically an inflammation of the joint capsule. It can apparently go away itself but could take a long time so not useful if you are wanting to be active. There are some exercise examples on here if you search the archives.
Good Luck.