I logged back on to give an update...I think it is improving! More dried out and red than anything now. He used regular bar soap and just did it in the shower. Of course now he is picking at the flaking skin and creating another problem.
Here is something interesting. He did have thrush at one time, several years ago. It was from using an inhaled asthma treatment and not rinsing his mouth afterwards each time. It was quickly taken care of with Antibiotics and hasn't appeared again. I wonder if that is connected. Though we tried Nystatin and something else that was a combo medicine and that didn't really help. And regular antifungal cream has been used lots of times without change.
I doubt he has a vitamin deficiency because even though he is a teen, he eats really well-frutis, veggies but maybe. A vitamin B supplement couldn't hurt to try.
Thanks for the feedback--this turned out to be a great place to get information.