Hi Brendan - in situations like yours it is always very good to have your shoulder in "hand". An inspection of the shouder rythm - mm mass - and all the testing we can do. However - it does sound like you maybe have a shoulder instability - or be slightly hypermobile in this joint. Sub-luxations of the shoulder is not uncommon - and you did the right thing in resting - but unfortunately the sub-luxation keeps occurring - according to your description. I would have it looked at by a shoulder specialist for you to put together a strategy moving forward - strengthening etc. Good luck !!!