This duckling was perfectly fine until about a week ago. One evening I went to check on them and he was flopping to get around, the day before he was walking. There are no noticeable injuries of any sort. He was with the momma and 7 other ducklings. I have brought him in the house and he is in a large tote with pine chip bedding, water, baby duck food and a stuffed bunny. He is getting niacin, brewer's yeast and poultry booster . We have tried a hobble with vet wrap (didn't work well) and with a hair thingie and medical tape (was toooo tight). He gets physical therapy in the sink filled with water daily for approximately 20 minutes at a time. What else can we do????