I have 2 10 week olds that have a rattling and gurgling sound when breathing. No other symptoms. No swollen or running eyes, no sneezing, no coughing, NOTHING. They are eating and drinking. No other birds in my flock (including 20 more 10 week olds that are from the same hatch) are having these symptoms. What is it? What should I treat with? Doxycycline is unavailable at all of the feed stores around me. I do have sulmet and vitamins on hand. Help please!