Hello. I'm a nurse and I'm going through that same problem. What it turned out to be was a tear from rough Intercourse. Tell her to sit in a SITZ bath just enough warm water to cover the area add some Epsom salt an a table spoon of apple cider vinegar. Heals it fast and also great for pain relief. She should also be checked out by a doctor because it can also be a severe yeast infection or bacterial vaginosis and shell need some medicine to clear it up.
Conditions like Bacterial Vaginosis, Candidal Vulvovaginits/vagina thrush (fungus),Trichomonas vaginalis infections , or herpes simplex (only if one of the partners are transmitting it).The signs of vulvovaginal inflammation include erythema (redness) of the vagina and vulva, vagina fissuring (cracked skin), edema (swelling from a build-up of fluid), also in severe cases, satellite lesions (sores in the surrounding area).
All of the above mentioned conditions should be evaluated by clinical examination or lab investigations when once symptoms start to aggravate.Prescriptions will include regimens to fight against their domain like Anti bacterial for bacterial infections and Anti fungals for fungal infections.Administration of choice is topical or oral depending upon the rate of healing or severity of symptoms.But options for prevention, debridement or healing support remains the same for any factor.If you participate in sex during this period,you also should start a regimen (both partners are treated for STD's or UTI).
As said broken skin heals by it self but needs to be taken care as there are good treatment plans available.Clear all your doubts with your Doctor and come up with some questions if you do not understand anything.
Looks like the vaginal mucosa has been ruptured or broken as a result of some possible cause may be due to inadequate lubrication or friction.
But the contour seems good, no suppuration or redness around the broken skin.Suggest you not to have a sexual intercourse or masturbation or insertion of virtual devices until this heals away.It not only causes bleeding upon forceful intercourse but also a risk of acquiring UTI or opportunistic infections.
Since you are clean,devoid of any possible STD's I suggest you undergo a clinical examination during its healing,less likely as Herpes chancre,but could not ignore it as torn mucosa always brings about new infections (mostly bacterial,fungal).Any how application of topical anti biotic creams like erythromycin or neomycin could prevent other infections like to occur during healing time as this broken skin heals by it self.It takes 3-5 days to have a primary closure which needs debridement with iodine and topical application of Antibiotics.
Bepanthen(Panthenol)is a baby cosmetic emoillent/moisturizer cream which has no effectiveness preventing from further rupture/infections though it accelerates wound healing.But unless the broken area is devoid of any possible microorganisms,closure by healing is not recommended since it increases risk of systemic infections like UTI,Cystitis etc.
But however meet your Doctor and take good prescription.