I have 9 8 week old sussex chick, there are a couple of them that are sneezing and wheezing when they breath. The are not gasping for air and they do not act like they are having trouble breathing. They are eating and drinking good, and act normal other than the sneezing and wheezing. They are still in the brooder at night, is it just dust? Should I be concerned? Should I give them anything for it? If so, what should I give them? THANKS