Ever try a gluten free and dairy free diet? Try cutting them out for a couple weeks.. then add one back in.

My brother had severe acne as a teen in the 60s-70s, he washed his face (gently) with a wash cloth in the sink with plain water as warm as he could stand maybe 4 or 5 times a day about 10-15 minutes or so each time. That cleared it up within a week or two. He kept up that regimen whenever it flared up and it worked. Once cleared up, he did the same thing two or three times every other day or so and it worked for him. Seemed like the steamy water was what mainly helped a lot.

Overdrying can cause irritation and inflammation leading to an overproduction of sebaceous oil leading to more acne.
This works for some if you give it a short period of time. Wash face only once or twice a day with a mild cleanser like Cetaphil ( no scrubbing!) and apply a few drops of Squalane (from olive oil)  oil  to a wet/damp face and massage into the skin. It should absorb well after a minute or two with no oily residue.
The squalane oil has to be of a small molecular size to ensure absorpion. Regular olive oil won't do, and doesn't absorb well. The BEST product is squalane oil made by Neova. (No I don't sell it) and is a bit pricey at $45 or so, but an ounce will last at least 5-6 months. His skin will feel better immediately, and in time a natural balance of skin oils will occur without inflammation.

Skin Bracer. Although an aftershave, it works magnificently to clear up skin.

Tightens pores, that's the tingle.

I never had a bad acne problem, but when I did get some acne, and I started using Skin Bracer, my skin was cleared of any acne and other blemishes.

Females should use it, too, if they have acne problems. Use it. It works.

You might try looking into oil-cleansing.  It sounds weird and counter-productive, but my skin just glows when I do it for a couple weeks.  (And I'm almost 40).

Rub strawberries on his face. Let it sit for fifteen minutes and then wash off. It works very well

Try avoiding all dairy products.