Two days ago, my 15-week old hen was completely fine in the morning. A few hours later, we found it by itself near some flowers, not moving. We found no external injuries, and kept it in the house in a box. It couldn't move its legs, wings, neck, and mouth, so we had to pry its mouth open to force feed it some water. Every few minutes or so(especially when it receives outside stimuli such as us touching it) the hen would suddenly jump around, then return to its previous state. This is happening less and less. As I only have 3 hens, I'd really like to save this one. What should I do?