This morning when I went out to feed and water my flock, one of my 6 month old black sex link roos started sneezing. It sounded like a high pitched bark and startled me when I first heard it. I tried to catch him to get a closer look at him but no go. He also keeps his beak open when breathing. None of my birds showed any odd symptoms yesterday evening. It sounds almost like he has a cold. He's still active although his eyes do look a little dull. The rest of my flock are not exhibiting any syptoms. The weather here has gone from hot and dry to cold and wet almost overnight so I'm assuming this has something to do with it. Any insight would be a great help. I do have a place to isolate him if necessary. Thank you, in advance, for your help!