is your chick wheezing at all? I would definitely put some vitamins in it's water. What about appetite? Sometimes, when they stretch their necks and look like they are yawning, it can be gapeworm. I would look that up and see what you can do for it.
I have a hard time thinking it may be gape worm, that occurs mostly in older birds that have had outdoor access. It comes from worms, slugs, ect. So if your chicks arnt free ranging eating worms and such It's not gapeworm.