A couple days ago I noticed one of my 17 week old babies started sneezing. I took note but left it alone because they tend to sneeze every now and then. Well it has gotten worse each day. It's been about 3 days now and all my chickens are sneezing and 3-4 of them sound congested and gasp afterward. I am seriously concerned and have no idea what to do. After much reading IB sounds the closest to their symptoms. I have no vet to see chickens. I added ACV to their water, I've given hard boiled eggs just as a boost. Also yogurt. They are eating & drinking fine. Acting fine too. It's been extremely cold here. Below zero this whole week. Their pens are clean and no ammonia smell. I have approx 45 birds in an 8 x 18 coop. They've been staying indoors all week due to the bitter cold. I'd appreciate ANY advice!!! TIA