I am very new to chickens and my current 5 month old flock is my first. 3 days ago one of my Legbar cross hens was panting a lot and looked pale in the face. I gave them all iced water and frozen blueberries. She did eat and drink with the others. However over the next two days she was staying in the run or coop rather than join the others free ranging. Although the weather is no longer hot, she still seems to pant a lot. I have not seen any abnormal poop. Any ideas? Should I separate her in a pen of her own? I just don't know what to do for her. The first two photos are of my sick hen. The last photos are my well hens.