To give her some relief right now, I would mix over the counter neosporin and hydrocortisone cream. Mix it about 50:50. Apply it to her vulva. Apply it every few hours. It is not toxic if she licks it.
If she licks her vulva, the lesions will get worse and will not heal. You an buy a plastic elizabethan collar, to prevent licking, from a larger pet store like pet smart.
I would also give her benadryl, at a dose of 1 mg per pound of dog every 12 hours, to help with allergies and inflammation.
Has anyone addressed her allergies and how to control them? It really sounds like allergies to me.
Food allergies and environmental allergies would be at the top of the list.
Beef, chicken, lamb, corn, wheat, and soy are the most common food allergens. Food allergies develop over months to years.
To determine if she has food allergies, she would need to be put on a completely hypo-allergenic diet for 6 weeks. The name of the hypo-allergenic diet is "hills z/d." It is a prescription diet and you have to get it from a veterinarian. There are no over the counter completely hypo-allergenic diets. It is only about $10-$15 more a month so it is not that bad if it fixes the skin issue. If her skin improves, then you know it is food allergies.
She could also have environmental allergies. This is called "atopy" or "atopic dermatitis." The dog's skin comes in contact with the allergens and then they are absorbed into the skin causing an allergic reaction. Your vet can do a blood allergy test to see what she is allergic to. Then she could receive allergy shots to desensitize her to the allergens. The allergy shots are 50-75% effective. We also treat atopy symptomatically with antihistamines, shampoos, topical creams and sprays, cortisone, and immune suppressing medications.
I am also wondering if she is allergic to something her vulva comes in contact with. After she comes inside, I would clean her genial area with a sensitive skin baby wipe. This will remove any allergens.
I hope this helps.
If you have additional quesitons, please reply.