Welcome to Just Answer and thanks for your question. I would consult another doctor about this, perhaps your gyn or Women's Health nurse practitioner. It may be bacterial vaginitis. With her weight it is difficult to keep clean and dry, especially if she is still leaking a little urine. The weight may also delay the start of her menses. If she is developing dark areas on the back of her neck, underarms, or inner thighs, it may be a problem called PCOS which includes insulin resistance and weight problems among other things. A sensitive medical provider would probably try a round of antibiotics just in case it was BV to start with.