What Causes Rashes And Spots While In Humid Places?

Hi i am 21 years old, 6ft 1 inch, 75kg, and have good medical history but have oily skin.



When i am in humid places around the world i get very bad spots and rashes all over my back, shoulder and tops of my arms. I have been to hot countries such as the Canary islands and Greece and have not suffered from these, however i went to the USA to a very humid state (Pennsylvannia) i always seem to get these horrible and irritable spots. My skin is always exposed to the sun but it seems that the sun creams irritate the spots even more. I have tried antihistamenes which help, but do not stop these from happening. I need help as i am going back next month and do not want to have to go through this all over again.