Hi! I am a first time duck owner. We have one week old runner ducks. One of the four is still the same size it was a week ago. Three days ago, it appeared to have a hurt foot and was hopping around on one leg. Now it is wobbling around on its belly unable to walk at all. We are making sure that it gets food and water but it has us worried. What could be the problem and is there anything we can do to help it. We have named this little girl Cocoa and she is our favorite of the four. We don't want to lose her.