I have small slightly itchy blotches on both sides of my back where my kidneys are?

Viral? Allergic? etc: Blotchy reddish rashes can occur when the blood flow in the tiny vessels at the skin's surface change, such as in eczema, an allergic rash, a viral rash, a fungal rash, or in reaction to changes in skin temperature. Sometimes there is flaking on the surface. Rashes are hard to describe in words, so an in-person exam or a video conference with a doctor is needed to help find the diagnosis.

Don't know what it: is. 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.