Hi 
Thanks for your query
You seem to have developed skin pigmentation due to 
tanning.
Topical medications can definitely be of help to you in reducing the pigmentation to some extent.
I would advice that you should use a lightening agent like kojic acid and vitamin c combination over the affected areas. This is a simple, harmless lightening agent which can be used for as long the blackish pigmentation is there.
Also ,try not to touch the area too much. 
Also ,try not to touch the area too much 
Use proper sunscreen (spf>26) before going out in the sun so that the lesion doesn't darken any further 
Take a diet rich in vitamin C and antioxidants like Citrus fruits and lots of salads 
If after all the above measures, the pigmentation tend to persist, then i would advise that you should see a 
dermatologist as there are various other measures for the treatment of pigmented skin like the use of 
chemical peels, 
dermabrasion etc which a dermatologist can decide according to the type of 
scars.. 
Hope it helps 
Wishing you speedy recovery 
Dr Geetika Paul