Instead of self treatment, consult a qualified dermatologist.
If the spot is painful, apply clindamycin
and benzoyl peroxide
till it heals. Later for the dark spot use a cream containing kojic acid/glycolic acid/hydroquinone
for 4-8 weeks at night. Apply sunscreen with a SPF of 30 during daytime.
Best would be to consult a dermatologist
Hope this helps you.
Dr. Rahul Nagar