Most clinical words ending in “itis” means inflammation of some sort – for example, peritonitis and laryngitis. A bursa is a fluid-filled sac which prevents muscle insertions rubbing on bones within your body.

A shoulder injury, however caused, can cause months (or even years) of pain and restricted movement. You may not even remember the incident that caused it! Some injuries to the shoulder build up over a long time; repetitive movements can cause overuse injuries, much like those that happen to the wrist muscles (RSI). 

If you have pain in your shoulder, it is wise not to try and self-diagnose; some shoulder pain can be referred from the neck or back. Make an appointment with a physiotherapist if the pain does not go away within a day or two.