Have Itchy Tingling Red Rash On Shoulders, Chest And Neck. Have Shingles. Cause And Cure?

Hi. I was diagnosed shingles about three weeks ago, when a rash formed on top of my chest and a couple of other lesions, and was in significant pain and agony. I still have the unsightly marks, though my pain has finally subsided. I have since now come out in a very itchy, tingling red rash over my shoulders, chest and neck, went to the doctors Thursday and he wasn t sure but said it s probably an allergic reaction to something, like detergent...Haven t eaten or changed any toiletry products, but am staying at my friends house and it appeared here and was itching in bed, using towel etc....What could be the cause? Could it be their soap, detergent or something? I m taking telfast one a day, this is now the third day but the rash and itching is still present and i am worried.