I ask about human antibiotics because they're usually in pill form. Animal antibiotics are fine, too, but the ones from the feedstore require mixing in water or injecting. If she has an infection you would want to treat with a broad spectrum antibiotic, but not sure if doxycycline qualifies.
Would duramycin be a good one to try? I can separate her in the coop so that she is the only one drinking that water.