Over a month ago we took in a duck that had been living inside someone's livingroom. They stated that it was about a year old. We notice the palnish in its bill and legs. It wasn't till we brought her or it home when we notice that it was unable to walk around that good. We fed it the scratch and grain mixer we feed others and dosed it up with vitamins. The duck has never quack and in the pass week has become aggressive . What can I do. It is not that way towards my other ducks which laid their 1st egg yesterday. I am not really sure of its gender and not sure if it has any handicaps due to malnutrition.