We got 4 production reds and 3 Wyandottes from a local guy who was thinning his flock to make room for Turkeys. One of the production reds started sneezing pretty quickly and I wasn't able to separate her. I treated my entire flock of 16 with something I found to treat these diseases at my local feed store and all of my chicks act completely fine. I treated the water for 2 weeks. However, the production reds are still sneezing and having runny poo. They act completely normal and are still great layers. Should I cull them since the others seem fine still or should I assume the whole flock has the disease now since it normally spreads and not all chicks will show signs. Of course I'd start all over in the future after thoroughly cleaning the coop/run. Just looking for opinions. Thanks!