I have 4 nine week old buff orpingtons. They have been sneezingand clear runny nose for 2 weeks. I am not seeing any other symptoms. Eating, lots of energy and no drainage from the eyes. I am not sure what I should do with them. I have no other chickens to worry about as they are my only ones. Should I let it run its course of treat them? if I need to treat what should I use.