What Causes Rashes On Back,shoulders And Upper Arms?

I have a rash, started in my hair and is now on my back, shoulders and upper arms.I have been to the demo. Dr. and did get a couple of cream prescriptions. It has been one month, it itches and looks like early shingles without the silver. I work out of town more than in and I out of town next week, what can I do till I get Back?