Hypoglycemia is common in small breed puppies
esp since we have bred them done to such small sizes
Their metabolism is so high at this size in relation to what they can eat at one time that they can literally run out of fuel
so make sure that you pup eats at least every 6 hrs if he's really young
if he's fussy some Nutrical or Karo syrup will at least keep him from sliding into a coma
as far as the playing issue
he feels more secure in his crate
but playtimes should be about him getting out and seeing the world
I'd close the crate door or put it somewhere he won't see when you want him to play with you
but remember that puppies do need their sleep time too
Mine sleep half the day
Never mind what they do the rest of the time
