I would start with a Neosporin antibiotic, see if that clears it up in 3 or 4 days. Could be a staph.
other things to consider would be soremouth(Orf), So I would wear gloves and wash your hands
Soremouth will run a 5 to 6 to week course
Another good product is Nustock for fungal and mites. not so sure how great for a staph, it is sold in the horse section.
Look over her body and see if you see anything else.
look on her mouth/nose/ears/udder
look at her pasterns. mites will often start down by the feet
obviously soremouth could also be on the mouth and face. Although I have seen goats with mites have yellow rings of scaley skin around their eyes.