What kind of wood is the box? If its OSB, it may have gotten some of the glue in its system from it, I had it happen about 10 years ago and they act funny, all were different symptoms and lost half the flock till the vet figured it out. Also outside temp will make them sick if its below 75 to 80 degrees and a breeze is pressent. Flooring in the pen should be wood chips to or they will eat it, trukeys will eat just about anything.