The mentioning of not using layer pellets was an offer of something to try to help them. Some ducks don't do well switching feeds, SOME ducks need starter longer, SOME ducks need extra niacin added to their diet. All were suggestions on how to help them.
In the future when posting asking for help on an issue remember to include the following:
Breed of duck (chicken, goose ect)
Age
Feed they are currently on
Did you hatch or purchase them
How long has the issue been going on
YOUR LOCATION (not everything is available everywhere)
Housing set up for the bird(s)
Then take a deep breath and try and allow others to comment and make suggestions. Don't assume anyone is saying you don't know what you are doing if they don't directly say it. Allow the open dialogue to continue as many times solutions will come from openly discussing issues and bouncing ideas out. It's like brain storming, ideas need to be mentioned to keep the thoughts coming.