I have a Pekin Drake that was walking fine one day and then the next he wouldn't walk on one of his legs at all, and now he can't walk on either even though he never moved from where I put him after he stopped using one of his legs. I have had him sitting on straw and he's been eating and drinking water when I put it in front of him. I've been changing the straw under him every day so he doesn't get sick from sitting on his own poop. Is there anything that I can do to hopefully get him walking again? Or are his legs possibly permanently damaged?