Well! We got 5 chickens (don't know the exact age) in April 2016. I say We but they belong to my dad . In October we got 5 more. These were 6 months old. In December one of the original girls stopped laying eggs and became sick. We took her to the vet and he said he could feel a large mass in her stomach (not eggbound). The vet said it was likely a tumor and didn't give us much hope she would make it. A few days later we had her put down. They went ahead and did an autopsy... they found that the large mass was egg yolk! We made sure the rest were getting good feed, grit, free choice of egg shells & oyster shells. A few months ago another of the original 5 fell ill. Stopped laying, lost weight and became weak. A few days later she died. Yesterday, we lost another of the original. Unlike the other two this one never laid eggs. She looked older than the rest and we figured her egg laying days were over and she was just a chicken. We were okay with that. The only thing we could really say about her was that She had lost some weight. It was totally unexpected. The last two of the group seem okay. They are still laying eggs and eat everything they can. The new 5 are doing great but we worry that this is going to repeat. I've spent so many hours reading this forum but nothing seems to help me figure out what is going on. Maybe they were older than we thought? Anyone have any ideas?