Have you looked at the soap you're using? You may be using too much and the washer isn't getting all of the soap out of his clothing in the rinse cycle.
Try washing his clothes without any soap. Look in the machine after it has agitated (or if using a front loader, look at the window about halfway through the first wash cycle) to see if there is any soap sudsing going on. You might be surprised to see suds in a washing you added no soap to.
He could be one of those guys whose sweat reacts to the fragrances used in your laundry soap, too. If you don't see any sudsing in the the wash without soap, try a different soap, maybe one without any fragrances added, and see if that helps.
I had something of the same problems, and lol, it turned out to be too much soap AND a chemical reaction to the fragrance. I switched to one of the products without fragrances, and cut the amount of soap I was using. Problem solved:)