The history and description in this very brief question directs me towards the diagnosis of Heerpes Zoster,although you havent mentioned any vesicles or blisters but i think you need to see a dermatologist
to see the lesions live and then proceed. If its what i am thinking of then it needs to be treated urgently to avoid further complications in the future.
I am afraid i cant comment further because i need to see the lesions,and without that its not possible to reach to a final diagnosis.
thanks very much and all the best.