Need help with sick duck possible coccidiosis

[Buzz2035]

Added also have been giving her nourish I think is the name added vitamins to her water

 

[Crazy Maizie]

The joints do look very swollen. So, I imagine she is in a lot of pain. I appreciate you sharing the pics and more thorough info. Her poos look like she is having issues - digestive and dehydration.
Maybe there is nothing you can do for her. If she's in that much pain where she's not wanting to eat, it might be best to think about her quality of life. It is a hard decision when it comes time to euthanize an animal, but it might be what is best for the duck.