I was hoping this was Nicks yorkie too. To the OP, I think you are doing an amazing job looking for who the owners are. Your taking great care of this sad, scared little boy , and he is starting to come around. Poor little guy may have had it pretty rough.
Things happen for a reason. this little dog has come into your life for a purpose. Sadly, he may have been dropped off or abandonded.
My thoughts and prayers are with the little Yorkie. Renovatedgirl, thank you for rescuing him.