I just picked up 3, 4-day-old ducklings from TSC this morning. They've already settled in nicely. However, I've noticed one of them is having problems with his/her left leg. I don't think it was having problems when I first got them. They have nutritional yeast in their food for niacin. What could be the problem? Last year, I had a duckling with a similar problem, but I thought she had gotten trampled. She ended up dying at about 8 weeks from seizures after lots of special care. I really don't want a repeat! What could it possibly be? I'm not 100% sure on the breed, but I think it is a pekin.