Please help I have a small mixed flock and one 4 year old chicken has started sneezing. She is showing no other signs of ill health, no mucus or discharge around the beak or eyes; good colour comb and wattle; eating well; feathers, vent, etc all looking good. I know I'm supposed to separate a sick chicken but is she sick? Could she just be sneezing or does it have to be a respiratory disease? I put apple cider vinegar in their water, use wood shavings for bedding and they free range in the garden. Does anyone have any suggestions?