It seems that you got super added bacterial infection on the part due to severe itching
producing scratches and soreness.
Go for one oral antibiotic medicine for 3-5 days.
Go for oral anti-fungal medicine like Flucanozole 150 mg once in a week for4weeks to get complete cure.
Apply anti-fungal cream locally.
Keep localhygiene clean, dry and airy.
Ok and take care.