We have a 4 month old bardrock pullet who was very healthy until last week. We originally purchased her, one more bardrock, and 2 buff orpington pullets when they were about a week old. We recently introduced some younger chicks into the coop with them (as well as a americauna who is about a year old). All were doing well, and then last week, this pullet (Patience) started limping. We thought that one of the others might have jumped on her when going after treats (these very sweet chickens all turn into vultures if there is anything other than their normal food around). For the first day, she just limped. The second day, her leg seemed to give out on her. We removed her to a separate pen, then the following day, put one of the buff orpingtons in with her for company. After 2-3 days, Patience seemed better, so they were moved back in with the others. She was able to get up on the roost, but then came back down and seemed worse, and we moved her to a separate pen yesterday, and she seems to be getting worse still. She sits back on her haunches (?), but will get up for treats, and still has an appetite. We believe that she is in pain, however. When she does get up, she isn't able to stay up for long. Anyone have any ideas of what this could be, or what we can do for her?