I was wondering if it could be a vitamin deficiency. Try poultry Nutri Drench in their water, it has alot of minerals and vitamins. I'd recommend stop using it after about 3 days though,it can cause diarrhea. Also try vitamin B complex in their feed as well as calcium. The vitamins and be bought at a pharmacy and crushed into a fine powder and sprinkled in their feed. Try it for about 5 days and see if it helps. Probiotics might help...plain yogurt, canned beef catfood and scrambled egg all mixed in their feed. The catfood and egg provide protein. I hope your yall's chickens get back to normal, I've never had to deal with something like this before with my chickens.
