About 3 weeks ago the first hen seemed to have sour/impacted crop and stopped laying. I treated her and she still is not eating or drinking the same or laying. Then the other day I noticed another hen sitting away from the flock and her comb is smaller then the others. I have watched her closely and she is not eating like the others. She has stopped laying 4 days ago. The other hens are being mean to her now. I feed them fermented layer feed and some treats. What should I do I don't want the others to get sick.