Hi! I have an original flock of 4 month olds and recently added 2 americanas that are supposed to be around a year (my bf choice, not mine-he wanted eggs asap, I wanted to raise them) and have had them for about a month now. I have noticed that one of the new americanas always has a runny nose (both nostrils) and has a gross fishy smell to her face when I hold her. I also noticed once her nose was bubbling a few days ago. The other one who came with her has a slightly runny nose but only occasionally. They do not seem lethargic nor do their eyes seem puffy nor do I notice them sneezing. I called the feed store and they told me to give Duramycin for 7 days in their water. Question being- do I treat the others that do not show symptoms? Also, they told me that the chickens had colds....I have read elsewhere that chickens do not get colds....I am new to the chicken world and def do not know anything about their diseases yet except what I have glanced thru her on the site. Thanks so much.