You can purchase a tube of Nu-Stock at your feed store. It'll be in the equine section and apply it to her bare bottom. It'll heal the area in no time and will prevent picking. Shake the tube well and wear disposable gloves when applying it. Apply as needed.
Give her buttermilk mixed in boiled...
Did you smell the odor of "yeast" in the air around her vent initially, a very foul odor?
Here's a good link for you to read abut vent gleet which can be either fungal, bacterial or protozoal...