Thanks for your query.
Ideally i would like to know a little more about your symptoms before suggesting a remedy.Skin hyperpigmentation
can be due to various causes ranging from as simple as an acne
to a drug reaction.But based on your explanation it seems to be a bad case of sunburn
likely compounded by the harsh weather conditions in trichy.i would suggest you to apply a sunscreen lotion everytime 30 minutes prior to going out in the sun onto your face neck and arms.Several good lotions are available such as suncross or neutrogena with a higher sun protection factor.Also if there is any itching apply calamine
lotion on the patches to soothen them.I would also recommend you to avoid as much sun exposure as possible. Thanks