My 11 month Black Australorp has been making this weird coughing/sneezing noise for the last few months. Some days are better than others. When it first started happening I quarantined her and gave her antibiotics for a week. No changes. I tried Vet Rx Poultry Remedy, still no changes. I keep their coop clean and dry and they get free range time whenever the weather permits. I've tried oatmeal treats with ACV. I've tried every herb I can think of in the coop. None of the other hens have shown the same problems. My BA is otherwise perfectly healthy. Laying regularly, eating, drinking, breathing just fine. Any ideas?