I seperated my little guy from the others just in case and put him in a clear rubbermaid small tub next to their big rubbermaid clear tub so they could see each other. I massaged his neck to and that seemed to help.
Take one of the capsules and poke a hole w/ a safety pin and hold his beak open and squirt in as much as he can handle, same w/ the infant drops, I did this in the morning and evening. I also got the Naicin that I could break open and put that into his food. Also heard brewers yeast was good. I was worried I was giving him too much vitamins but that's what I kept reading to do. Plus some of the Vitamin E and Infant drops didn't always make it in his mouth, half ended up all over both of us, but we kept at it for about 2 wks, at 1 wk, I could already see a difference, but like I said w/ ours, he was really bad, he walked around like his head was tucked in his wings, had a very hard time doing anything. He's great and healthy now and lives w/ his siblings now. He's 3 1/2 wks old now.
I hope the vitamins help! What kind of duck is he??