Have you ever wormed them? I would start there. There are many great articles about wormers on this site you can search for. It is spring and things are waking up, including parasites.
Edited by newwestchick - 3/6/16 at 7:29am
thank you! i think i am on chicken md overload. too much seaching is leading to me to think it's anything and everything ie/vent gleet. I am happy to know that vent gleet is not contagious and since their vents are fine i think I can take this one off the table of concern. thank you for your response! MUCH appreciated