I have a pet duck who is a little over 2 months. I heard banging so went to check on him and thought he was dead or dying. He keeps throwing his neck back amd tips over on his back. We thought maybe he chocked on his food since i just fed him so my husband tipped him over but didnt notice anything. After about 2 hours of him throwing himself back and us trying everything he finally stopped. Well we noticed if we turn the lights off he does it again. Can anyone help? Is he sick? My baby boys love him and always run to see him in the morning, what can we do?