Grind down the chick crumbles, or feed wet mash. I can't tell you how many times I've noticed chicks not really eating because the crumbles were too big.
Bbutter, my post gal is the same way, carries them like they were crystal. And I'm sure the majority of postal workers are great thoughtful people. But every now and then, you will met a psychopath, even in the postal system.
I'm glad you called. You have to be pretty sick to shake chicks. That's alot of chicks together to be cold, but I guess it can be. Kathy has some good ideas, but maybe they're the effects of whatever happened.
I guess what I would do is make them wet mash from the crumbles, maybe some...
I think you should contact the hatchery and see what they say. It could be something they came with.
I know a few years ago, alot of people's chicks were dying, it turned out to be from the hatchery. Call them. You have lost too many . Tell them.