Talk to Dermatologist on Itching On My Arm

from past one month i m having itching on a specific area of my arm. there was no kind of pimple. with the increasing passage of time that area of arm had developed a scar there and whenever anything touches it it really irritating. i avoid itching on it. but the intensity of itching is also increased. what should i apply on it? should i need to consult a doc? if so what would it be specialist in? Does this is an alarming symtom of any desease or so? if so please tell me which tests should be done thanks