We ordered 20 assorted bantams and 4 barred rock and 1 new hampshire red. We have had them for a week and all have been doing GREAT until tonight. I got home at 5:30 changed feed and water and at 6:30 we had one dead 2 panting and couldnt stand walked back to check on them after giving them water and they were dead plus two that had no signs. I now have another panting and cant stand. What do I do? Any ideas on what is wrong???