Dear Concerned ., Thanks for writing to us. In all probability , the history of prickly sensation is suggestive of subcutaneous denaturation of protiens in the lower stratum of skin and subsequent allergic reaction that ensues against denatured protein underneath producing prickly heat rashes on the exposed parts of the body. Kindly apply soothening creams/lotions such as Lotio calamine over the affected area generously and do not allow exposure to Sun for a three to four days. The lesions will subside.If there is fever pls take him to local doctor as it indicates infection.