Diagnosis for Betta losing scales!

[FishChem]

The scales on my bettas head have been disappearing over the last few days. No behavior change; healthy. Not sure if it's an infection or a wound he keeps messing with. I don't know how to help him heal. The area's first white where a new scale has disappeared, then goes red. It seems to just affect the skin so far. Started at several small locations on his head it's now one big spot and has been spreading towards his left eye.

[Delapool]

Check water parameters and then would suspect bacterial as seems to be getting worse.

[V227]

If you can rule out a wound with a fungus, then the ailment might be lymphocystis, a viral infection. No cure, but not a fatal disease. Fish infected can get white patches, even white or pink bumps anywhere on the body. Fish usually eat and act normally. The only treatment is to beef up the fish immune system with quality food and water. I believe one of my Denison barbs had lymphocystis A small white growth would periodically appear around his face and mouth then vanish in a month or so. I think this virus is similar to a cold sore. This is just an educated guess. Good luck.

[FishChem]

I think he has heater burn. The wound on his head has been healing and the whites going away. I think it's not that virus looking at him (hopefully). How can I make sure it doesn't get infected as it heals?
Another mark appeared after I changed the water a week later. Just like the first one appeared after a change.
I didn't turn my heater off either time so it must have gotten burning hot getting exposed to the air. That's my thinking thus far.

In other news I checked the water parameters and it's just as it should be. I also I added a little salt and some stuff for his slime coat.

Is there anything else I should do?

[Delapool]

Most of the time just clean tank water will allow healing I find.