I am sorry to hear about this, he is lucky to have a friend researching options for him. Unfortunately, it is impossible to diagnose what is going on without an exam and knowing his medical history, but perhaps these resources can spark some questions to ask his doctors.
I am guessing the jungle rot you are referring to is Athlete's Foot that has spread -
I wanted to pass along this article, Brighten Up Blemished Skin , while waiting for more response. It offers several suggestions that may help. Let us know if you have tried any of the products mentioned.
Wishing you clear skin in the near future. Keep us posted on how you are doing.