Wheezing can also be a sign that their vents are clogged. I had this happen to a chick once. I freaked out and called a very expensive vet, just to figure out that I needed to pour a small amount of saline through her nostril to clear the dust. After a couple weeks, when she got a little bigger, she was perfectly fine again. Although that doesn't sound like what you're dealing with, it can be a problem with young chicks.
Baby chick's dying!! help - Page 2
Chickens are hatched fairly self sufficient. They eat, drink, and walk around on their own from day 1. However, they're not great at socializing! They will walk on top of one another for several weeks. This can injure or kill newly hatched chicks and, although uncommon, these kinds of injuries and deaths can happen.