I would call a vet. Babies go downhill very fast. Is he weezing at all? If so it could be pnemonia. We had a baby that got extremely sick from this and was a miracle she pulled out!
Mercury - 2002 bay tb gelding
Cobalt - 2006 bay sw warmblood x QH gelding
Cricket- 1996 chestnut tb gelding
Bella Blues - 2007 Australian shepher/Blue heeler mix
Titan W. - 2008 Jack Russell Terrier