I’m so sorry!! You said you could feel her bones, do you think she was under weight? Have you wormed them recently?
I had a hen who was starving to death but I had no idea. She hid it so well. Kept up with the flock, until one day she just couldn’t. I brought her in and she was so boney! I had no idea because her feathers hid it so well. She was eating/drinking, so I couldn’t figure it out. I later discovered she had a roundworm overload and was starved to death because of it. She came in and died in one day, it was so quick. So I always throw it out there just in case!