Several of the hens in my big coup look like they are dying all of the sudden. They are standing or sitting with their feathers all ruffeled up and their eyes closed. Their face and comb and wattles look pale/dried up. They stopped laying eggs and only move if you nudge them. I didnt change feed, location or anything. These birds are 2-4 or 5 years old. They are speckled sussex, golden buff, wellsummer and white leghorn. They seem to be having normal poos. any help would be appreciated! ps. I have started them on antibiotic and vitamimes.