My polish hen has started breathing with her mouth open and making a high pitched squawking sound. She stretches her neck when she tries to exhale and is having audible breathing......I can't really tell if her nose is stopped up. I have isolated her from the rest of the flock but am very worried about her. I have given her tetracycline in her drinking water but am debating whether I should be treating her for gapeworms. Any suggestions?