My 9 wk old dark braham seems to be having problems breathing. She stretches her neck out,opens mouth and at times swallows several times. She sometimes coughs too. This has been going on a few days but seems to be getting worse. We quarantine her to see how she is eating and drinking. Does anyone have any ideas of cause or how to treat? She had 5 days of tylan 50 couple weeks ago due to frequent sneezing when I got her. Any suggestions would be so appreciative!