I have a small flock of backyard chickens. 11 young hens and 1 rooster that I have raised in my home from 2 or 3 days old. My Welsummer, Summer was 28 weeks old, laying 4 or 5 eggs a week, eating good, running around and playing with the rest of the girls. She enjoyed her treats and looked very healthy and beautiful. Clear eyes, no runny nose, no sign of any illness. On Friday when I went to put them away for the night, Summer was outside of their 50 x 50 foot chicken yard. As soon as I let her in the gate, she ran to the water and starting drinking. I did not see anything wrong with her and I put them all in their 16x16 foot enclosed chicken pen which is attached to their chicken house. When I let them out on Saturday morning, I didn't notice any problems with Summer but I couldn't find her at first yesterday afternoon. She was laying under the tree and when I started to pick her up, she got up and walked away, seemingly fine. I thought maybe she was starting to go broody as she was laying in a box when I locked them up last night. Today when I let them out, she was laying next to the water in the enclosed chicken pen dying. I picked her up and she was barely breathing and she looked at me, closed her eyes and died. Please give me an idea of what could have happened to my sweet Summer. All of my other chickens appear healthy. I feed Layena (pellets), give them only healthy types of treats ie. watermelon, apples, pears, etc. and they also get Chicken Scratch at night for a treat to get them into their covered enclosure (16x16 foot covered dog kennel). Any help would be appreciated.