The treatment for post inflammatory hyperpigmentation includes various skin creams like hydroquinone, azelaic acid, corticosteroids, tretinoin cream and laser
treatment. Other treatment options are laser
treatment, Chemical peeling or microdermabrasion. You should consult a dermatologist and discuss these treatment options with him.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided.