I understand your point of view; however, right now you are shooting in the dark because you really don't know why your young birds are dying. Treating with Corid is fine IF you know your flock has coccidiosis, but you're subjecting your birds to a needless vitamin deficiency if they don't have...
The periodic wet brown stools that most healthy young chickens have will usually be red and watery if a chick has cocci. For the most part Corid is a good preventative treatment for coccidiosis, but it has the side effect of stripping vitamin B from chicks.
I think you were smart to refrigerate...