I hope it has cleared up by now. I read somewhere to try vitamins and even asprin.....not sure if that will work though. I don't have ducks but I had a problem with turkey chicks and their legs. Their foot would turn out and eventually wind up backwards. Apparently a nutrient called "Choline" was responsible for the development of tendons and ligaments. I didn't believe it at first because only a few birds were affected (why not all if it's a vitamin deficiency). However, once I started adding Choline to their diet it never happened again. Egg yolks have lots of Choline so I give my baby birds chopped eggs in their food regularly for the first month.