Ok not a vet but lots of animals thru the years.
Good news is . maggots as gross as they are, are a very good thing on a wound. because they only eat dead meat and infected meat. so now that you know they're, there.. clean the wound really well you can pull the maggots out or flush them out. ( you'll have to check everyday for more) there are some excellent medicated ointments you can put on the wound that you can get at the feed and seed store one of my favorites is Corona lanolin-rich antiseptic ointment for horses cattle small animals and pets.. ( works great on scraped knees too ) its great being antiseptic you don't have to add an additional one to it. good stuff.
as far as the protruding vent. I know, I know but life on the farm .. we do what we have to right?.. so clean very gently the little vent.. using CLEAN patrolium jelly coat the vent inside and a bit around the outside too. and gently push the vent back inside. ( this happens to dogs too especially small toy breeds when they have a pup with a very large head.) anyway. gentle is the word.. ( bad thing is that once this has happened it might happen again, just keep a watch on her..)
there is a book I have, its the old version of the Storeys chicken book. I do believe it has a section on this also I know they have a new version out too..
as far as her sleeping on the floor not a roost. can you put like a piece 2x4 or two stacked ( broadside)short enough that she can hope onto it, but wide enough to hold her little body but where her fanny will hang over the edge. she wouldn't have to hold on to anything either with her little feet but she'd be off the floor.
I hope this helps you and if your like me, everyone is worth it. even a little chicken.
blessed be )O(
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