Hi there,
Thanks for your response. When I first saw my sports doctor he identified tightness in the thoracic and first and second rib. He also normally treats the neck because I have tight scalenes and have had a few facet impingements on the left side (it's the right side of the levator scap which spasms). But your advice is very interesting and it's something we haven't considered.

My physio and I are also testing a new theory (previously thought my injury was due to a scap instability) to see if my problems (levator scap muscle spasms, biceps tendon pain etc) are stemming from an anterior g-h instability. In some ways it could be possible if the instability puts stress on the levator scap, RC and aggrevates biceps. Of course the problem is that every test which has been done, I've tested negative for g-h instability. Do you think this is possible? To me, it seems like we've gone two steps forwards and then three steps back because my scap stability has improved significantly and I am quite strong.

Also what are the treatment options for glenohumeral instability? I've been asked to go back to do external Wikipedia reference-linkrotator cuff exercises (which I dislike) to try and get the g-h sitting better but my physio thinks that if there is no improvement in 4 months I should see a shoulder surgeon to consider the options of doing an arthroscopy to see if there is a tear in the joint which needs repairing. Also are there other less invasive options which can provide similar accuracy in diagnosing tears? Maybe it's time for another Wikipedia reference-linkMRI to see if the pathology of my shoulder has changed since the original MRI I had 3 years ago?
Help is muchly appreciated