I have a 1 year old female call duck that can't seem to walk very far before she lies down and just lays there for long periods of time. When she starts to walk again, she crawls along on her belly for a few steps and then starts to walk. She appears to walk normally (no limping) when she is up and walking. She is eating and drinking and pooping normally too. I have felt all over her body and legs and do not feel anything abnormal. Her belly is soft, her legs feel ok. I am totally at a loss with her strange walking. Any ideas??????