Background: I have a backyard flock of 4 birds; 2 - 12wk old pullets and 2 - 5wk old chicks (in isolation). Both groups are on deep litter. I use ACV & garlic in their water daily. Symptom: 5wk old chick with what appears to be a swollen sinus on one side of her face. It is unknown how long this has been going on. I have been away for the past 7 days for the holiday. The chicken sitter did not notice it. Observations: The tissue all around the eye is swollen. The eye itself seems to function normally. There is no red inflammation of the surrounding tissue or eye. The eyelids are not 'swollen shut'. I don't see any discharge from the nose or eye. The eye does not seem to be overly watery. There is no smell. I have not observed any wheezing or sneezing. The swollen area does not appear to be overly sensitive to touch. The bird shakes her head more than usual but not an excessive amount. The bird also scratches at it with her foot. Her appetite and activity level appear normal. Treatment (so far): Carrot water & saline eye wash. Research: I have and have read Damerows Chicken Health Handbook. Every ailment that mentions swollen sinus also mentions wheezing and other symptoms I have not observed. Question: Can it be as simple as a sinus infection? What can I do for the bird? What should I have done to prevent it? Thanks.