Single sore on vagina. Doesn't seem like herpes what could it be?

I've had a single sore on my vagina increasing in size. Only one location.

How would you describe it? Is it under the skin or on the surface? Is it like an ulcer? Does it hurt to touch? How long has it been there, and has it changed in appearance during that time?

I would go get a swab done on that spot by a doctor to be sent to a lab to be cultured.