Hi there. Relax. Dont jump to conclusions. It is most likely due to friction that a 'traumatic' ulcer has formed in this region. Use a topical steroid-antibiotic-antifungal cream that you can purchase over the counter or check with the pharmacist for one...this hould resolve or decrease at least 50-60% symptoms in 24-48 hrs...assuming there is a mild bacterial/fungal overlay. If not resolved, then you need to visit your dermatologist
or gynecologist for a further opinion & needful I still think the problem is a minor one & will resolve with this intervention. Cheers & do give us a shout when rid of this ulcer. Wish you well.