Hi Stu

Do you think that sitting with a slumped posture and protracted shoulder girdle has just started to stress the glenohumeral? Try sitting up and extending your thoracic spine and then reposition your shoulder girdle (lift it up and back). If this improves the shoulder 'clicking' carry on and even tape your scapular to help retrain this position.

Dont worry about the 'clicking', I don't see many people who damage their shoulder in bed (unless they have a proclivity to jump off wardrobes!)

Steve
Hallamshire Physiotherapy