Suggest Cure For Persistent Itching On The Arm

Hello, my question is: On my left arm, approxitmately 4" above and below the elbow I have an itch that comes and goes and seems to be coming more intense and frequent. I have been using hydrocortisone cream (1%) but that is not working anymore. I live in Florida and wear t-shirts all the time, could this be sun related? Help, I'm starting to scratch my arm raw.