My 9 month old Barred Rock hen began sneezing 2 weeks ago. She doesn't have any other symptoms - no watery eyes, crust about the face, swelling, loss of appetite or energy, or decrease in egg production. She lives with 2 other chickens, neither of which are sneezing or showing any other signs of illness. I've added apple cider vinegar and a bit of citricidal to their water - is there anything else that can be done besides watching her? I captured a video of a few of her sneezes - they seem to come in spurts. Thanks for any help anyone can offer - I'm at a loss since there isn't anything besides a sneeze to indicate what the problem is.