The chicken was eating good but was a little lazy so I decided that she should get some light and fresh air. Till about two days ago she was the fastest and most active one. The moment I put it on ground one of its leg seemed hurt or something. She started lingering. I came back after two minutes and she was struggling to stand up!! I helped her get up but her fingers were closed(straight) so I made her sit but her heart and breathing rate(she opened her mouth too) spiked!! She tried so hard to get up but couldnt. Her wings got puffed up i put water and food near her and ate and drank. All this happened within 5-7 minutes. I waited for another 5 minutes but she got worse. So i put her to sleep. Any idea what could have happened?