What Is The Itchy Rash On The Coccyx That Is Spreading All Over The Body?

My mom is 70yrs old, has an itchy rash started in the coccyx area, includes her back. Now she has a rash under her breast. Has worsened rash in the perineum and is c/o hemorrhoids. She has had shingles many yrs ago. Do you think this sounds viral?