hi.thanks for your query..
From the clinical picture described, I feel you have something called Melasma.Although it can affect anyone, melasma is particularly common in women.The symptoms of melasma are dark, irregular well demarcated hyper pigmented patches commonly found on the upper cheek, nose, upper lip
and forehead. Melasma does not cause any other symptoms beyond the cosmetic discoloration.Treatments to hasten the fading of the discolored patches include:
Topical depigmenting agents, such as hydroquinone
(2%) creams available OTC in many countries
It is extremely essential to use a broad spectrum sunscreen throughout the day , with repetitions every 3-4 hourly,not only when outside, but also even indoor or while cooking/using computer etc.Please use a medicated sunscreen e.g..Cetaphil and be very regular in the same and melasma is increased by UV exposure. The sun exposure you had might have caused it to flare up.Also it is important to do a rigorous sun protection while on depigmenting creams like lomela.
U can do a few sittings of Chemical peels from a dermatologist
as these help more in exfoliation and lightening.They are also safe when done properly.
Hope this helps..Take care