Sick Bernice

Sunday it was 107 degree out, I went out to check my girls (Bernice, Francis, Gladiolus and Lulu). Burnece was nowhere to be found. I eventually found her hiding under the ramp in the coop, she was laying down and panting. I went to pick her up and noticed an odor, I took her over to the water hose to cooler down and she would not stand. I noticed her bottom was very swollen and red so I lifted her tail feathers and saw a maggots coming out of her vent. I immediately took her into the house and gave her a warm Epsom salt bath, removing all the maggots I could. She was weak couldn't stand and was laying on her side. I put some cedar shavings in a tote and separated her from the others. She is in the garage. I left her there overnight it was plenty warm and went to check or the next day, she was sitting upright but not standing. I checked under her feathers again and it appeared to be newly hatched Magette's. So I gave her another Epsom bath. I put some fresh watermelon in the tote with her and she immediately started eating.
I have googled several different things, she has a very swollen belly and bottom she has areas with the maggots have eaten but I have not seen any more Maggots sense. She still cannot stand on her own she spreads her wings to prop herself up. The Google search made me wonder if she has vent fleet or something else. I have kept her bottom clean and have been putting antiseptic spray. She is still very swollen this is day six. She started standing today but can't walk, she just spreads her wings for support. I don't know what to do. She is eating and drinking but has a swollen bottom and can't walk. The maggots appear to be gone.
What should I do to help he walk? I would love to get her back with her buddies.
Should I be worried about the Wild ducks that keep coming into the coop and eating their food, should I worry about disease from them. I'm at a loss, I don't know what else to do. Please help!!!! I love my chickens. Is it vent gleet or a fly issue. What are her chances? I'm at a Lois. Your help is much appreciated. Bernice says thank you

Found another thread with this same issue. Apparently, according to user my three chickens, it's called flystrike. Here's the thread.

https://www.backyardchickens.com/t/364589/help-hens-vent-covered-in-maggots-treatment

There may still be maggots in the wound, and/or they may have transmitted infection. I think you need to give a strong antibiotic, and use a systemic antiparasitic such as ivermectin. FLYS OFF or SWAT would be appropriate ointments