It could be a mix of all three, sadly, @Leia .... I was mid 40s when it happened first time to my left shoulder. So pretty lucky to get nearly 20 years out of the manipulation. Then it happened about 8 years ago to my right shoulder as well, with rotator cuff & bicep tear as well as frozen shoulder, and that one needed arthroscopic surgery.
All good now, but I think the meds have mucked with it too, as it has also had an ultrasound in recent week!! grrr
It all just sucks, really :(