I have several RIR and ISA Browns. One of my hens began acting different a few days ago. Then I noticed that her comb is almost colorless and laying over on its side. Now she's almost dragging her hind end. I know she can walk, I've seen her, but it's infrequent. She's isolating herself from the others and once she's in a spot that she's chosen, she just stays there. And she's lost weight. I've checked her vent and all seems clear there. And her belly isn't oversized so I don't think she's eggbound. Please give me any and all ideas of what you think it could be!