I have a rash on my back/spine (about the size of a 50 cent piece)?

So I went to the docs and she said I have shingles (she got another doc to check and he said shingles straight away). But I wanted a second option so I went to another doc and he said it was a cold sore (I thought cold sore only appeared on the face???) The rash burns - actually my whole back feels Itchy/burning, the rash has little white dots and is raised and red. Does anyone know the difference between the two? I have never had a cold sore before - but I know one of my friends always gets them (maybe I accidently shared her drink). I have been very stressed lately and I have had the chick pox before....??? I’m only 26 and health….!!!