I have a terrible rash on my back and i am not sure what it is. have had about a month and very itchy. is it shingles?

Impossible to say: There are many potential causes of "terrible itchy rashes." how can a doctor here possibly tell you what it is without seeing it and knowing more? There are limits to a forum like this. However, it is probably not shingles, as shingles is usually extremely painful & generally not very itchy. Please see a doctor in person for an accurate diagnosis.

You may: You might have seborrheic dermatitis or lichen amyloidosis. See your dermatologist to find out.

Can't diagnose with: this info. This rash needs to be visualized & a history needs to be obtained in order to make an accurate diagnosis. Sometimes lab testing or biopsy is necessary.