Desperate for some advice here. This is the first time purchasing adults bird. : ( We purchased 11 birds from a very reputable chicken breeder. About a week later a hen had one eye swollen shut and then both eyes swollen shut by the next day. I isolated her, deep cleaned the coop with a bleach solution and started Duramycin 10 (4tsps/gallon) for the entire flock. The next day, I found two more had a watery bubbly eye. The first isolated bird started eating and drinking on her own again after three days on Duramycin 10, but one eye is still swollen shut. I was able to get one eye open and have been putting ointment (puralube and Neosporin) on all the sickly eyes. My question is this. The breeder advised Duramycin 10 in the water for 14-21 days. After reading posts online I notice most are using Tylan 50 injections. The girls aren't laying yet so a withdrawal period is not an issue. The sickly eyes have not improved yet (it's now been four days on Duramycin) though no one seems worse and no additional hens have started symptoms. Should I switch to Tylan 50? How long should I wait for all symptoms to disappear before I freak out? Any advice would be very much appreciated. I am so worried for my girls. I have never dealt with a respiratory illness before.