I have a batch of chicks almost a week old. They were all fine walking well but suddenly 1 by 1 they started having trouble walking and their bellies are kinda pasty. Looks like their down got wet but it's dry . (Not pasty butt) My son said the pine shavings were wet because he had spilled some water. Not sure if maybe they slept in them wet like that. Also was feeding medicated feed but switched to non medicated. Could one of these be the culprit? If so what should I do?