Hi thanks for posting.
You have developed post inflamatory hyperpigmentation
treatment depends on the depth of pigmentation. which can be assesed by your doctor.
If in the superficial layers of epidermis
you can get tca peel,or lactic peel done once in 15 days along with mild steroid cream in the day and combination cream like lomela(it contains tretinoin
and momatosone)at night
If dermal layer is involved,
It takes a longer time to go, peels, mesotherapy,laser might help
oral preprations containing Beta carotene
can be taken.
avoid sunexposure. use sunscreen every three hours during the day
you have four months to go , hopefully your face will be better.
all the best