My barred rock, about 26 weeks old, suddenly started limping badly. She can't put weight on the leg. I see no sign of bumblefoot or injury, it doesn't seem broken, no swelling or extra warmth. When I hold her, I notice the bad foot doesn't curl up tightly the way the good one does, and the leg trembles when I hold it gently. I have her isolated in a separate area of the pen (with her best buddy) so she isn't tempted to run around too much. She's eating and drinking. Any ideas?