Please help me figure out what's wrong and save my two remaining hens and my guinea flock. I had 4 pullets between 10-12 weeks. They went into their tractor run for the day this morning looking healthy and plucky and this afternoon they were acting a little sluggish. This evening 2 are dead and a third is acting very ill, not eating or drinking. The last one is still acting fine but I have them separated tonight. My guinea flock free range and seem to be perfectly healthy. They have constant access to fresh water and starter grower and have had nothing out of the ordinary to eat.