So for about four-five days I have been dealing with the exact same thing. First one large healthy buff chick started sneezing. We didn't have a spare brooder space so we just watched it. No nasal discharge, eyes fine, but slightly lethargic and appearing unable to sleep due to the sneezing bothering it. It probably sneezed three to four times during a ten minute sit with it. We also have pollen going on like crazy here right now and I have had to have the windows open on my sun porch to keep the temp regular and fresh air circulating. So there is a fair amount of pollen in there. We got it Vet Rx and all chicks have had Rooster Booster probiotic/ electrolyte additive in their water frequently from about day two due to some pastey butt. Then the next day all three buffs in the flock of about 24 started sneezing. So strange. they are larger and better develped than their flock mates. So I ran out, grabbed a cardboard box and new brooder lamp, waterers etc also antibiotics just in case. Grabbed nutra drench supplement. I also was putting some vet rx or similar essential oils in a diffuser a bit of a ways away from them but in the sun porch to help hopefully keep the dust down. It was also way less dusty in the carboard new box away from the mass of the flock so I was hoping this would help. It did not so I began antibiotics. Their breathing seemed a bit labored and I could hear a crackle in their breath when I picked them up. Also their gizzards seemed kind of swollen and when I would massage them a little the crackle was also present- But again NO drainage from the nostrils nothing else. After the antibiotics the next morning they seemed perkier although still sneezing. They weren't drinking barely at all and the antibiotics were in the water so I used a syringe and made them drink some of the anitbio water along with electolyte water to re- hydrate. They are still perky but still sneezing. Now a large Olive Egger from the crop has began and been moved into the sicky brooder. I am just at a loss!! Ive irrigated with syringe on that one too. (no more buffs in the flock they ALL came down with it) All four are perky and eating and drinking but still sneezing and somewhat crackly breath. I think one more might have come down with it too. I am about to go nuts!! Am I just over treating some chicks with pollen reaction or general sneezing??? Does anyone have any tips??? Thanks much in advance!!