It hurt. Everything hurt. He was sure that his shoulder was probably cracked in a few places or probably smashed in. At any rate, moving it was unbelievably painful. Eventually pushing himself into a sitting position, the merman looked down at the injury, taking note of the torn skin and anything else he could see or feel. 

Broken. His shoulder was definitely broken. 

Without much more thought besides how it would be easiest to twist into the best position without hurting himself more, his first instinct was to lick it. Even just a little bit to dull the pain somewhat. So, after some more painful maneuvering, that was what he did, not particularly aware of how strange it might seem to the others.