My little call duck, windou, is pretty old...id say 9 years or so. Today I went out and my flock was out pecking around but lil' Windy was flipped upside down laying on his back. Lately he has been lethargic i thought maybe its just the cold. I picked him up today and thought he could spend sometime inside. He was a pig so i let him sit in the bathtub. Mind you this duck LOVES WATER but he tried grooming himself and almost fell over each time. He also did this thing where he stretched his neck out in front of him and lost his balance, almost falling over. I also noticed one eye is shut and the other one is weakly open. I'm wondering what it could be...Please help. I have had this duck for so long!