@Ravynscroft @Miss Lydia @casportpony @WVduckchick may have better ideas. I don't know much about ducks.
Can you tell us a little more:
Where are the wounds located?
Any photos?
I can't advise on herbal treatments, I don't know anything about them.
It sounds like the wounds are infected since you detect an odor. The wounds need to be cleaned out and debrided (pus/dead tissue needs to be removed, rub/scrub with a rough wash cloth to loosen dead skin/pus to get to pink tissue that bleeds slightly). Flush the wound several times a day with sterile water, saline, Chlorhexidine (Novalsan) or Betadine. Apply something like Vetericyn Spray or triple antibiotic ointment to the wounds.
This is where I get a bit lost...if I understand correctly ducks need to be able to get in water to clean their nares, groom, etc. daily(?) So....if possible having a clean pool/tub of water for her to use daily would be the best. After she is done, you need to re-flush the wounds and re-apply ointment. Keep her on clean dry bedding.
As for not eating, I don't know what would entice her so someone will have to make suggestions. I am thinking she is going off food due to infection, but could be wrong.
Treatment suggestions may help, but she may need antibiotics to help her recover.
Just my thoughts.