You have what is known as PIH or post inflammatory hyperpigmentation.
1. Sunscreen and sunprotection- this forms the absolute cornerstone of management. You need to be on this for the duration of any treatment .
2. Apply a kojic acid cream for at least 8 weeks.
3. Chemical peels such as glycolic acid can help. You will need 4-7 treatments over the next few months.
4.
Vitamin A such as tretinoin can help.
The best treatment is a combination of the above.
Next Steps
You can refer my health feed on "10 Tips for Brighter & Younger Looking Skin!" by Dr. Jolly Shah Kapadia - https://www.practo.com/healthfeed/10-tips-for-brighter-younger-looking-skin-16374/post
Health Tips
"Understanding Chemical Peels" by Dr. Jolly Shah Kapadia - https://www.practo.com/healthfeed/understanding-chemical-peels-8036/post