I've found updates in other posts like these helpful so I thought I'd share one here as well.
I administered the last dose of enrofloxacin yesterday morning. She seems to be recovering and perking up quite a bit, so I've decided not to extend past the recommended 5th day (10th dose).
A few hours after that last dose, I started feeding her some Rooster Booster, which contains lactobacillus / probiotics to help her restore her microbiome. The container instructions call for 1/3 tsp per gallon of water, but I added that much to a half-cup just to kick start things. Will begin adding yogurt tonight.
I've let her play outside a few times and she's fairly energetic for a good 30 minutes before she slows down. When resting, she still has her tail pointed down quite a bit, but not nearly as much as before.
Since yesterday, she's been shedding a ton of feathers, so perhaps this is a result of molting? The angle's comparable to a couple of other hens undergoing molt.
I haven't seen any egg in her droppings lately and she hasn't laid from the time we brought her in. I'm fine with her never laying again, so long as she's healthy. I should note her droppings have been obscenely large, probably because she holds them until I let her out (outside and indoors. To my chagrin, she loves leaving a dropping every time I set her aside to clean her bedding...!).
Diet now consists of the layer feed with a tiny bit of scratch mixed in. We also have some leafy greens (not of the variety that prevents calcium absorption like kale) in the mix. Also added egg whites last night as a treat to help with the molt.
(finger for scale, from yesterday ~5 hrs after last dose of enrofloxacin)
We're going to keep her inside for a few more days to monitor. I hope the treatments have helped put her in the clear or at the very least, bought her some more time to live in good health.
Let me know if there is anything I should watch for / any other treatments I should provide at this point. Thanks again everyone for chiming in with advice and suggestions!!
Finally, on a side note, our rooster's had fowl pox for the past two weeks. It seems like it's gone from dry form to wet and he's stopped eating (dripping him bits of yolk / rooster booster in water). I might make a separate post, but other existing posts have been helpful so far. We've kept him
8-10ft away from our recovering hen. Let me know if I should add more distance to this or if this is sufficient for now.