If you want to repel flies while the bird's wound is healing, a little Permectrin 2 mixed in a quart bottle sprayer goes a long way and has a residual Martin's brand and others don't. A little goes a long way and you don't spend as much money. Just spray the feathers around the vent and inspect it daily as it heals.
If you see rat droppings around, then there are rats. Around my barn I use Tomcat locking bait boxes with block/chunk bait. Rampage is a good block bait because it poisons rats and doesn't have a secondary kill factor. The reason you want to keep rodents out of your bird's area is that they are spreaders of Fowl Cholera, E. Coli, and Salmonella. Pick up feed at night and clean out waterers daily. I use Oxine to spray down the waterers, let them sit overnight, rinse and fill the next morning. I use plastic waterers since I use supplements from time to time.
Maintain a well drained yard during winter, and keep the grass cut to avoid vectors (darkling beetles, slugs, snails) for worms. Keeping the grass cut also prevents thick, fibrous chutes of weeds to exist which chickens will sometimes stuff themselves with and get impacted crops. Start a worming program. Some folks worm their birds twice a year, some more often depending on environmental conditions. Albendazole, which is the ingredient in Valbazen, kills all the worm species and is safe when the proper dosage is used. Dosage is 1/2 cc orally with an absent needle syringe for standard breeds, and 1/4 cc for Bantams. Worm once, then 10 days later and don't eat eggs for two weeks after the last dosage. That one hen with loose droppings? If the bird seems active, alert, has an appetite, but often has diarrhea, then she might have worms.
Some drugs to keep on hand for protozoan infections:
Corid (Coccidiosis)
Metronidazole ( for Canker or Blackhead)
Sulfadimethoxine powder (Coccidiosis, Cholera, also a good antibacterial for intestinal infections like "The Greens")
Antibiotics to keep on hand:
Enfloxil 10% injectible (same as Baytril)
Tylan 50 injectible
1cc syringes and 22-24 gauge needles
Ravap EC is a great premise spray. Permectrin 2 is a decent one also to prevent or treat mites and lice. A 2 gallon tank sprayer makes premise treatment easy. For disinfectant I prefer Oxine AH and use Biophene sometimes as a premise disinfectant around the barn, yards, and coops.
I'm hoping, in a day or two, she'll be ready to reintroduce to the flock. Her scab is flaking off, exposing fresh, healed, sealed skin. 
will that matter?? and I have Tylovet Soluble. Suggestions on whether or not to use an antibiotic & which one of those. I don't know how to describe what her wound looks like. The maggots cleaned it up pretty good :/ The color is like a whitish off white color and the top layers of her skin are pretty much gone...almost feels squooshy/spongy? I saw her limping yesterday but didn't notice the wound because I looked. It must've been very small.
