I have 5 Pekin ducklings. They are a few weeks old, just starting to get a lighter tint to them but still fuzzy. They have been doing great up until today. We are having an easter dinner today and I thought that it would be nice to take the ducks and let the kids play with them in the grass. So I caught them (had to run them down) and put them in a transfer cage. They were all fine then. When I took them out (they were in the cage for about 10 minutes), one cant walk. It kind of waddles on its knees. He acts like he cant stand all the way up all of a sudden. What is wrong? I couldnt detect any breaks or dislocations. I hope he snaps out of it. I dont want the kids to see him like this.