My Friend Has A Rash And It Is Very Itchy.

My friend has a rash and it is very itchy. She tried Benadryl, she also takes about 4 showers day and night. She has taken oatmeal bath and creams for itchness but nothing seems to work. She had this nurse look at her back because that is the only place she gets this rash. She said it is underneath her skin and it is rough she seems to think it could be shingles. Could you help us or if you have another suggestion for us. Thank you