Welcome and thanks for posting your query to the forum.
It seems from your problem that you have allergic rash
oer the chest area. There could be many factors causing this rash and especially sunlight aggravated by sweating over it.
Once the sunlight causes irritation over this area further sweating creates more problem.
For the betterment I would recommend you :
- to have sun protection particularly by cotton clothes.
- To do cold
water compression over the affected area.
- You can apply over the counter available calamine
lotion in a very thin layer.
- For the itching or irritation you can take "levocetrizine" under medical advise.
Despite above things if oyu are not getting relief then can meet a dermatologist
for the best of diagnosis and treatment.
Lastly kindly do not scratch or rub the rarea as can lead to further aggravation of the problem.
Hope these informations are helpful.
"Wish you good health"
Dr Sanjay Kumar Kanodia
MD (Dermatology & STDs)