My 23 year old nephew has a bright red back, and is in terrible pain (bringing tears to his eyes) We tried hydrocortisone cream, benadryl, with no results. Took him to urgent care & they told us it was just a sunburn, & prescribed Prednisone.-- not resolving @ all. I can't see a "rash" at all, just bright red skin- on his back only. Any idea what it might be, or suggestions?