One of our chicks seems to have symptoms like human allergies. He/she, "Grendel," was a little smaller to begin with, and would sneeze off and on. No nasal discharge, no lethargy, normal poops, eats and drinks normally and doesn't get picked on by the other chicks. She is growing and getting fluffier all the time - she's a four week old silkie. It seems worse when I fluff the pine shaving bedding, so we made sure the brooder room was better ventilated. She sneezes more if I pick her up, if we go outside, any kind of stress really. Sometimes she opens her mouth to breath for a breath or two like her nasal passages are blocked - but this is very infrequent. She loves to be held though! She does dust baths in my lap and lies on her side to be scratched under the wings. I thought it was a cold at first but it's been nearly two weeks. Is is possible for a chick to have allergies? I use water with electrolytes, I was thinking of switching to apple cider vinegar for a while and seeing if that helped. I have also heard of using a "probiotic mash" but am not sure what this is...any ideas?