Hello my son's baby pet rat is lethargic and breathing at a med. pace. Isn't moving or drinking milk which he feeds him by bottle. His name is Zero he was given to my son by a friend my son loves this rat but it looks like he's dying. He's only had the rat for about 4 days. He was very active about an hour and a half ago now no movements no eating or drinking milk. What can my son do to get the rat back active???