So I made a stupid mistake and got 6 new hens and let them in with my chickens after only 4 days by themselves. The chickens came from a place where they were over- crowded and badly over- used by the roosters so they looked terrible but I figured the best way to help them was to let them with my flock and start giving them good food and lots of attention. Well two days later 1 of mine gets sick quickly with nasty eyes, coughing, terrible chest rattle and slinging some yuck around, within and hour I can see it appearing in 3 more chickens. From reading it seems like Tylan 50 is the best option so I orally gave all of my chickens 1/2cc. They all seemed to perk up some except the first one the showed symptoms and she is gasping when she breaths. From what I read I should give them 1/2cc 2x a day for 3 or 5-7 days (I have read different opinions so not sure) The new chickens are gone and I have completely cleaned my coop top to bottom. Am I doing the right thing? Is there anything else I can do?