Update: I called my vet and she suspected the scent of the carpet cleaning solution. She suggested Benedryl liquid. She said to give a fraction of the children's dose according to his weight, 4.6 pounds at this point. I haven't given him any yet. I'm watching him. He ate his supper well and hasn't been sneezing in the last 4 hours so hopefully trips outside to potty have cleared his nose. Thanks for responding! I love this sight!