Treatment for pressure sore on left cheek of butt?

Home health used Duoderm bandage for my mom. Creams that were used were Aloe Vesta and Sensi Care. Can also use a diaper cream from baby section in store.

Okay, don't laugh but this one is highly rated by nurses here in Louisiana. Can order online. Boudreaux's Butt Paste. Walmart has it.

Sounds like an incipient pressure sore, but you've caught it early. My Mum has had several of these - I use hydrocolloid plaster to protect the skin (it's pricey but worth it, and you can cut it into smaller pieces). But the main solution, according to our doctor, is to keep the pressure off the affected area and allow the blood to circulate in the skin, to stop it developing into a full-fledged sore.

I use a cheap square inflatable pressure cushion (costs around £13, so maybe $18) , which you can buy on Amazon. It's made of softish blue plastic with a lot of holes in it (think of a waffle with actual holes where the indentations are). You semi-inflate it, and then put it under the part with the sore. When the person moves, the air inside moves around too and the pressure on the skin changes. I've successfully used this to help heal Stage 2 - 3 sores. You can put it on a chair or on the bed. Cheap and effective, and saves a lot of money and grief.

How did the appointment go?

It's a pressure sore, by now hopefully you have seen a doctor. If you are both active, maybe not sit so long from 7 - 11:30. Put some music on and dance some minutes or hours away. Camoseptine, ask pharmacy they will know, is a barrier for skin, Ointment A & D, Eggshell pads, or other sort of pad. Every hour get up and move a bit. I will start thinking about that for myself, as I sit more nowadays....

I agree, the donut may not be a good idea. I think they are mainly for the lower back. Could it be a boil? A hot compress may help.

There is a cream to treat these wounds with. That and a bandage will help. And wife's wound was bigger than I hand and as you described. She kept it active by scratching it all of the time.
It eventually healed with treatment.

You can force sleeping on the back by taking away the head pillow and putting a heap of three pillows under the knees. It takes a night or so to get used to it, but it is actually really good for back aches. It might be worth a try while things heal.

And a recliner chair can take most of the body weight off the bottom.

Donut cushions are not recommended any more because they tend to increase pressure on the areas not inside the hole, since the sore is on the cheek it is likely right where the ring of the cushion meets his bottom. The alarming thing about pressure sores is that the damage deep below the surface is much more extensive that what you see, that's why it is so important to catch them early. If you can get in to see your regular doctor tomorrow then I would not wait, and in the mean time he needs to stay off his bum.
https://www.agingcare.com/articles/what-caregivers-need-to-know-about-bed-sores-203147.htm