About a week ago my duck began breathing heavy. He was acting normal so i thought i would watch him. The next day he was breathing fine. Two days ago he started breathing heavy again and sneezing a little. Again this morning the breathing didnt sound too bad. Hes still eating great and playing, being responsive. I live in michigan and its been below 0 wind chill for awhile so hes been in my garage mostly (with my other ducks and chickens) i was letting him out to free range for most or at least half of the day but when its under 20, i keep the ducks in. Its ventalated and i change there pen every other day. None of my other ducks or chickens are sick. I did make him a vet appointment but they cant see him ntil monday. Im just worried and i dont want him to go downhill quickly although hes acting fine now.