have 6 buff orpingtons that are about 6 weeks old. We've had them a month now and all has been fine until Friday. I noticed a couple of them have one eye that is almost shut and real moist. Then they had a hard time breathing and just stood around gasping for air. My wife did some reading on here and bought some Tylan200 and Sulmet drinking solution Saturday. We started treatment and they appeared to be getting better. Woke up this morning and one was dead and the other was having a hard time breathing again, she died a couple of hours later. Anyone have this problem?