Do you know if she has any difficulty urinating?
Has she had normal urinations?
Is it a raw, ulcerated sore or more like a red, raw spot?
Just to be sure, there is only one isolated sore, none on her belly or groin area, just the one spot?
Well, there are only a few things it could be:
1. Yeast infection - which is fairly common around the vulva area, especially near the folds of the vulva. Often the skin is also red, though, so if it is just the ulcerated area and no redness of skin around it, this may not be the case. This is treated with a topical cream which can be bought over the counter that contains miconazole.
2. Bacterial infection - from an injury or in general. Most of the times antibiotics by mouth are needed but you can try a triple antibiotic cream such as neosporin on the area.
3. The blood coming from the vulva has to be from one of two places: the reproductive tract or the urinary tract. I would say this would probably warrant a urinalysis just to rule out any problem with a urinary tract infection or urinary crystals or stones.
Please let me know if you have more questions,
I would let them have a look. Blood from the vulva is always a concern, however, it is not urgent. You can definitely wait until tomorrow to take her.