He has a gurgly sneeze/cough. And when he breathes sometimes he makes a gurgly noise. Oliver is a bantam cock, six months old. I bought him at a flea market (Take my advice and don't buy from flea markets, too many sick chickens) along with a couple others. He's in solitary confinement, has had vitamin and electrolytes in his water along with duramycin for 5 days. His runny nose is gone, but his cough isn't...is this a really bad problem that I need to adress more seriously? Is there anything else I can do?