You could just position a tub in a dry space an fill it with fine sand, wooden ash and DE to make a dust-bath for your chicks.
If you suspect something poisonous, maybe even poisonous plants you could make some holy-thistle tea for your chicks. And adding humic acid (a special kind of activated...
Please don't get worked up. Take a deep breath and calm down. :hugs
We will all try and help you find out what is wrong investigating possibilities one at a time.