I was getting into the brooder box to make sure that my chicks had enough food. As I was shutting the lid, one of the chicks tried to fly out, and got caught in the gap. I opened the lid again and watched as he flopped around flapping his wings writhing. Then he got still and just laid there staring at me. I took him out, and he wouldn't hold up his head. I checked for any visible injuries and didn't see anything. After holding him for a little while, he fell asleep in my hands, I put him in a tub with some litter in it which is now on my kitchen counter. He's spent most of the time laying fully stretched out. While I've been typing this he moved enough to tuck his feet under him, and then fell asleep again. Any ideas on how to could figure out what part of him I hurt or how badly I hurt him?