That does look a lot like a burn...
One thing I'm concerned about is that you mention "the smell". If he has actively rotting or necrotic tissue on him this needs to be debrided and removed by the vet or it can cause infection. We use zinc-oxide cream on rashes and minor burns in people, not sure what it's supposed to be doing on a snake. I'm not a vet but based on what I've been trained on burn and wound care management in humans I would suggest the following until you get a clear answer from a vet:
Do keep him dry and clean. I would go ahead with the antibiotic soaks as recommended, but pat him dry afterwards. Any excess moisture will promote infection. If you can see any obviously necrotic tissue and if you feel comfortable doing this take some clean, dry gauze and after his soak gently try to remove it. If he doesn't tolerate it or it doesn't come off easily leave it until you see the vet. I wouldn't slather the cream on heavily either, just a light coat.
Maintain a stable, 85-90'F ambient temperature, even at night. Regardless if it's a burn or not it looks like he's lost a significant chunk of his epidermis/"skin", and while they're not like humans which depend on skin for proper thermal regulation, keeping the temperature stable and constant will help him maintain homeostasis and reduce stress.
Leave him alone as much as possible and let him rest in a dark place. Hopefully the little guy'll pull through!
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