Ducks walking weird

[ashes22]

I have had my ducks since easter (right around there) and they all have walked the same since I got them. A neighbor came by today and said they have a walking issue and do not walk right. I noticed when I had them that they all walk a little low but since they all did it, I thought it was normal. This is my first time owning ducks so I still have A LOT to learn. I have read some forums that said to give them niacin or brewers yeast. I went and bought niacin and I put it in the water right away 1 capsule (100mg) in a one gallon bucket. I was wondering if there was anything else I can do. They don't have any other issues (webs look fine, they drink and eat plenty) they are always going in and out of their "pool". I believe I have all males. I feel that if I had a female, I would have eggs by now. I was told when I got them they were around 6 weeks.