Poor girl!
Even is you don't see wounds or abrasions, sometimes they can suffer internal injuries or just trauma from an attack.
I'd keep her eating/drinking. Poultry Cell is good, but I'd consider giving 400IU Vitamin E and 1/4 tablet B-Complex daily. Ducks also need Niacin, but I'm not...
Photos?
I'd recheck for injuries that are hidden under feathers, look for bruising and abrasions on the legs/feet.
Work her through shock. Electrolytes would be a good idea. Keep her calm and separated in a quiet area.