i have post inflammatory hyper pigmentation as well. it is due to,allergic contact dermatitis to your lipstick, lip balm or tooth paste, long term allergy leading to PIH. My dermatologist has given me creams for treatment and i do see results, but she told me that i will see proper results after 6 to 7 months as it takes time.i will advise you to stop using cosmetics and see a proper dermatologist who will give you some products for bleaching according to your skin type. its so horrible, i can feel your pain. good luck