Duckling in question is about 4 weeks old and has been doing great until tonight. Got them out for their nightly bath, and they had fallen out of the tub but he still seemed fine. But now he cant keep his balance and keeps toppling over and throwing himself onto his back. I thought I had heard somewhere this can happen if they get cold so he is isolated and under a more direct heat lamp than his friends. He seems a bit better, but still cannot keep his balance and keeps falling over. Anyone have any ideas what is wrong? I'm not really sure what to do for him, but I dont want to lose him!