sounds like she may have a respiratory infection from that.
Get her on some Tylan or any oxytetracycline based antibiotics, these will help. There is no cure for respiratory infections, it's like a cold with use, just has to run it's course, usually 2-3 weeks, but the antibiotics will help fight off other infections while she's down.
Head shaking and labored breathing are usually signs of that, or she could have gap worms, not common in waterfowl, but possible, and they do the same thing.
Usually with respiratory infections, the eye's and sinus cavities will swell too, if that happens, she has CRD, Chronic Respiratory Disease (mycoplasma gallepsum) it is permanent and will always be carried by the bird. It will get better, but can re flair or be spread to other birds, hope that's not it, so far so good there with no discharge or swelling.
I would give her, Safeguard wormer 3 cc per gallon of water for 3 days, and the antibiotics mentioned above just to be safe.
As long as she's eating good and not loosing weight, she should get better on those in a few weeks for you.
If any other signs come up, let me know
Good luck