It sounds like he has a “chicken cold”. I would use hydration formula from tractor supply, also use vetrx on his nose/eyes, it will clean out the mucus. For additional help put vetrx in his drinking water with the hydration formula. Hope this helps.
I am new to owning chickens, and started off with 20 or so. After fighting off raccoons, possums (which do kill chickens), foxes and so on, I made a mistake of bringing in a rooster from another flock which had his own illnesses that I didn’t pick up on. Well, chickens started dying daily, they...