If you're worried about her being overweight, you could see if there are any threads that talk about how much call ducks should weigh and how much feed they should be eating on a daily basis.
Ah ha, Amiga has shared the calculations in this thread that I just found. It is very helpful...
I haven't had a duck molt yet, but could that be it?
What's her breathing like, any tail bobbing when she's laying down? That is sometimes a sign that the issue is egg related, in which case I'd try a little extra calcium.
Also, here in the states there are vet offices around that will do...
So glad that fox let go of him! How's he doing?
Sounds like his esophagus might have been damaged. Hopefully none of his organs, though. Maybe a vertebrae or rib got a small fracture in the whole ordeal?
I wish him a strong recovery!!!