I recently bought 3 new hens to add to the 2 hens I already had. One of the hens I already had has developed a blocked nose, is lethargic and when she breathes through her mouth I can hear a gurggling sound! I assumed it was just a cold due to stress of the newcomers/new germs bought in by the 3 new hens. But even now her symptoms have lessened, she's still not herself And one of the new 3 seems to be developing it as well...anything to be concerned about or any advice?? Thanks!!