Are you living in a place where nights grow longer and longer? In the Scandinavian countries all people gets a bit moody and sad in the winter it seems. So many people are tried and eating loads off chocolate and getting out more and more...
I really do hope your son will become healthy again! It must be like hell to see your kid being sick and knowing that you want to do everything and don't know so much. Can you take him to a better hospital? Sometimes a doctor that can give a second oppinion is the answer!!