What Causes Rashes Like Sunburns On Knees, Arms And Neck?

I have a rash on the backs of my knees arms and neck that look like a. Sunburn and are now peeling. I went to my primary. He did a ua, CBC and cmp. My urine had bacteria and protein. I constantly get kidney infections. I also have a blood disorder. Along w my rash i had inflammation in my joints to the point it was difficult to walk. Could this be lupus?