By the way - forgot to mention that Storey's Guide to Raising Ducks recommends 100 to 150 mg of niacin per gallon of water for symptoms of deficiency. That might help if you have some B complex or even niacin capsules around.
Right now since you are snowed in, do you have any B-vitamin capsules? I am not a vet, don't want to go too far out on a limb, but if it is a niacin problem, then I want to tell you niacin is B3, and you can also get some extra niacin from sardines packed in water with no extra salt. Brewer's...