it is difficult to know without looking at it...my feeling is that u may be having uriticaria or an allergic response...some people develop uritcaria in response to cold, hot, water, etc and it is bascially a allergic reaction. it may also be due to drugs or some type of allergy..at least that is my guess as i am unable to see your lesions..perhaps u can take a pic with a digital camera and post it..if that is the case, then u have done the right treatment..benadryl and an anti histamine, to prevent the itch, apply come lotion and use moisturizer
if the problem does recur, then it is best to see a dermatologist
hope this helps
