I found my adult lovebird at the bottom of its aviary earlier today. It is not able to fly. When it tries to do so, it turns upside down and I need to turn it back around. It has a foot that appears paralyzed, as it is limp and he can't use it. The other foot is fine. He won't eat, but I fed it a little Exact baby bird formula. This was difficult because it has its beak clenched tight to prevent the feeding. The stool is dark green. It is alert, is not puffed up, and is not in any apparent pain. However, it appears that its whole body is paralyzed except for the foot it can use to clench on to my finger. I have separated it from the other birds and am keeping him warm and comfortable. Please advise as to what the cause of this problem may be.