I have about three one and two-year old chickens that have developed a sound that I can only describe as a combination of sneeze, cough and hiccup. It's just an involuntary sound that reminds me of a person with Tourette's syndrome. There have been no other symptoms such as watery or crusty eyes or nose, unusual droppings, etc. that I have noticed, just the sound. They eat, drink, and are active. This has been going on for a few weeks now. They are in my main coop, so everybody there has been on quarantine. I tried a regimen of terramycin but that seemed to have no effect, and I don't want to keep throwing medications at them without some indication of what might actually be called for. The coop has a dirt floor, is at the edge of a wooded area, and we had LOTS of rain all spring and early in the summer, although approaching drought conditions now. I haven't tried worming other than DE in their food. I've kept poultry for 5 years and have dealt with predators and those pesky conditions that occasionally crop up in the birds, but this one stymies me. Any ideas from those with more experience would be greatly appreciated.