Suggest Treatment For An Itchy Skin Rash

hi, i have a prickly heat rash, that just started from a small patch of rough skin. it turned into a red very itchy lump, and then i got small itchy bumps all down my arm. its very itchy and is hot to the touch. how can treat it? i have had it for 2weeks. im currently putting ice on it which had helped but it doesnt seem to be going away.