Okay... That might be your problem. They really do need more than just scratch. It has very little nutritional value to it and no protein, which is a big nutritional requirement. They need to be fed a good layer feed and scratch should be fed in moderation, meaning that scratch should not...
Is the feed you are giving them fresh, free of mold, and rodents? Are they standing around with their heads tucked and are any of their feathers ruffled? Are they getting into any poisonous plants, flowers, or weeds? I would check all of the above, because I'm suspecting that it is something...