About 3 weeks ago I purchased 6 black sex link hens (all healthy) that are about 14-16 weeks old. Since their introduction to my flock of 12 (mix of black, reds and Americana) strange things have been happening! First, all but 2 of my original hens stopped laying. Now some have been acting odd! Kind of lethargic for a day or two then they seem to be back to normal. Now today when I went out one of my original hens is acting kind of tired/lethargic and her eyes are watery. I thought it was cocci so they are on antibiotics for that? But now I'm thinking it might be something else? Just stressing as I have 6 chicks inside and another 25 chicks scheduled to be delivered in April. I keep reading about disinfecting the coop well mine are free range in a very large horse barn and on multiple acres surrounding our farm. I would never be able to fully clean everything with a disinfectant. I just find it odd that they are sick a couple days then back to normal? Anyone have this occur or advice?