Hello, my name is***** and I have over 20 year of experience as a veterinarian. I am sorry to hear that D.O.Gee is having trouble with chronic dermatitis around her vulva.
It sounds like she has a conformation issue that is allowing moisture and urine to get trapped around her vulva, which is very irritating. This predisposes to secondary surface bacterial and yeast infections, which only irritate things further.
Of course she wants to lick, which will only add moisture and irritate already sensitive, raw skin and make things worse.
There are different types of defects but we can see a fold of skin tissue over the top of her vulva that shouldn't be there, the vulva itself appearing to tip slightly inward, or be recessed deep into tissue around the sides of her vulva.
It sounds like she has an immature, recessed vulva. Sometimes if these pups are allowed to go through a heat cycle the vulva enlarges and drops a bit, so it isn't so tipped in, and the folds of tissue over and around the vulva might decrease in size, or at least be less likely to be an issue if the vulva isn't covered so much by it. Of course she's spayed older and now, so it's too late to consider that as an option for her.
The best treatment long term is a vulvoplasty, where the excess fold of tissue is removed and the conformation thus becomes more normal, less likely to trap moisture and create an environment for infections to thrive. Here's a link to a webpage that discusses the condition and surgery: http://www.veterinarypracticenews.com/April-2009/Common-Cause-Of-Chronic-UTI-Has-A-Surgical-Solution/
In the meantime keeping the area clean and dry is essential. You can use hypoallergenic/alcohol free baby wipes to clean the area after she urinates and before bed at night. The ointment that your veterinarian has prescribed can serve as protection too, and decrease urine scald and moisture sitting directly on the skin.
Do not let her lick. If she is licking an elizabethan collar (cone of shame or lampshade collar) may be necessary.
In some relatively minor cases keeping her clean and dry will be all that is needed. But if she is suffering from recurrent skin and/or urinary tract infections then those cases will do better in the long run with surgery, as the conformation only seems to worsen with age.
Please let me know if you have any further questions.