My Runner Duck, Sage, was floating in her pool, as she tends to do every afternoon. I saw a perfect yolk in the pool, but didn't see any membrane or eggshell. She got out of the pool, but she was off by herself and seemed a little off. Sage has been laying every day, but a few times she has been laying 2 eggs in her pool -- one of them perfectly hard-shelled and the other misshapen (flat on one side) and without a shell . What could be going on?