We have a couple of hens that started having these symptoms about 3 weeks ago. First it started with just the sneezing/coughing then I noticed them gurlgling when breathing but seems to be mostly when they go to roost. They also move their heads funny sometimes like they are trying to swallow. I think some of them have runny poop and one has laid eggs at night without the shell - just the membrane around it. We got 4 hens the weekend of July 4th from a chicken farm. They weren't quite old enough to lay yet. Two of those are the hens that first showed symptoms. Last week my rooster Red started coughing and now my rooster Speckle sounds like he is losing his voice when he crows. They are all eating and drinking and acting fine otherwise. I have a total of 10 bantams, the 4 hens mentioned already, 2 young barred rocks about a month and a half old and 5 other chicks about 3 weeks old. The barred rock chickens came from our neighbors chickens - we put the eggs under our broody bantams. The 5 youngest chicks also came from someone else's hens. They free range all day then go to roost in hen house at night. I also have 5 mallard ducks out there with them that free range and have their own house at night. I had a kid pool that I let the ducks swim in and it got so dirty I cleaned it twice a day and put fresh water in it. Now wondering if the water made the chickens sick because they did drink it. The ducks and chickens share their water bowls too. I started putting duramycin in the water a week ago, but don't think I see any improvement. I got a few things from TSC - MetRX and Terramycin (cream). Not sure if they have a respiratory illness or possibly gape worm or what? WE are fairly new to chicken raising. They have pine shaving in the coop and get fresh water twice daily. We feed layer pellets and flock raiser. Any help diagnosing or suggesting what to give would be much appreciated.