I Have A Red Blotch On My Inner Shoulder That

I have a red blotch on my inner shoulder that goes away and keeps coming back it is dark red and when it comes back I get red blotches around my mouth and on my penis and even my butt gets real itchy I have been to my doctor he gave me a steroid cream that did nothing I have been to a dermatoligest but when I seen him it was gone well now its back again with all the same symptoms