Something needs to be done quickly for that duckling, Hopefully someone can help you figure out whats best for the leg. and so sorry about the duckling that died. 
this is for chicks but maybe something there that will help your duckling. https://sites.google.com/a/poultrypedia.com/poultrypedia/poultry-podiatry
Living in the Beautiful Mountains of Western N.C.. with 16 chickens= EE's, Game, Cochin bantams,Light Brahma, 13Muscovy ducks, 1Embden Gander,1 Toulouse goose, 3 mini Dachshunds, 1 mixed breed, pond goldfish, and a wonderful Husband who makes it all possible..♥
Living in the Beautiful Mountains of Western N.C.. with 16 chickens= EE's, Game, Cochin bantams,Light Brahma, 13Muscovy ducks, 1Embden Gander,1 Toulouse goose, 3 mini Dachshunds, 1 mixed breed, pond goldfish, and a wonderful Husband who makes it all possible..♥











