It looks like she has aspirated. I can't think of anything you can really do, it'll hopefully work itself out on it's own.
Gapeworm is *possible*
Ducks can get them. You could try and google to see how common they are in your area.
I can see ducks doing this if they swallowed something large and trying to get it down.. but after this length of time it should have stopped. Ducks don't have a true crop like a chicken, their esophagus just expands. You would see her chest bulging and hanging low if their were anything very big in there.
Other than a trip to the vet... i can't think of anything to do.
I'd try and pry her bill open and look specificially at her air passage (i forget the technical name of it) to see if you can see anything in there. It's that hole in the back of her tounge.
View attachment 3920569