Probably I acquired this condition from an unknown assault on my immune system from industrial exposure to some chemical, probably a hydrocarbon. Maybe a solvent (MEK) or gasoline or some machine tool solvent or epoxy hardener. Too many possibilities to narrow it down. I do not remember the skin rash suddenly appearing, more like I slowly became aware of the rash.
Changing my work (I now work at home, with very little exposure to synthetic chemicals) and moving to a much cleaner environment has significantly reduced the quantity and intensity of the rash. Also, I now eat almost no sugar, white flour or grease and no processed or fast food, this has also helped reduce the rash.