Hello. I have a flock of 15 chickens, all laying very well. A few months ago, I noticed that one had an eye that was not as pronounced as the rest. Now, the rest of the flock have swollen faces. No sneezing, no runny nose, no running eyes. Just really swollen faces. I tried tylan 50, duramycin, sulmet, and herbs. But, nothing worked! I sent in a test to the Poultry association, and it came back negative for mycoplasma. What is it, and how can I treat it?