Duck probably has worms, trying to get weight back up

[KitKatNB]

Hey I really need help and soon. We think my Indian Runner (female, almost 3 years old) has worms and we already gave her a dewormer. I read up on a few things and a lot of it basically said to get their weight back up to give them plenty of veggies and mix it with oyster shells for calcium. First of all, other than lettuce and cucumbers, what veggies can I give them? What should I avoid other than onions? What's a good way to help her gain weight
Edit: I clicked the diseases section and I'm unsure why it went into hatching

 

[oldhenlikesdogs]

Feed it some corn. That will put weight on a duck.