Help! Sick and injured mallard!

[BlueChai]

Two days ago, I went walking to a nearby pond with my partner and we discovered something very strange. There was a swarm of at least 20 mallard drakes, and on closer inspection I noticed that they were all mating with one female mallard! I chased the males away, to find a small and injured little lady. All the feathers had been ripped, exposing bright red skin, and she was missing many feathers on her back. She seemed ill, and didn't put in much effort to run or fly away. We took her home, and cleaned her off and fed her. The following morning, she looks worse. Her head is swollen and her eyes are swollen and oozing. We've been flushing her eyes and keeping her wounds clean, but I'm afraid she won't make it. I'm not experienced in ducks, does anyone have any ideas as to how we can help her? I'll get pictures up in a bit. Thank you.