Appropriate care for a blistered mouth burn?

Age: 27

Sex: M

Height: 6 foot

Weight: 170 lb

Race: white

Duration of complaint: 3 days

Location: roof of mouth, just behind teeth

Any existing relevant medical issues: none

Current medications: minoxidil and finasterids

A few days ago I burnt the roof of my mouth just behind the teeth on some hot tea and sausages. I've burnt my mouth or tongue before obviously, but it's usually just a bit of pain and numbness that fades.

This time however, when the numbness faded I noticed with my tongue a painful rimmed excavation as if a blister formed and popped. I'm unable to get a good look at the wound or submit a picture because of the location; I can't get a good angle in the mirror and my phone camera can't have flash on at the same time as a video to see.

I know to seek medical attention for drainage, facial swelling, changing or worsening pain, etc. What I don't know is how to treat or protect the wound since it's in a high use and dirty area of the body and I'm concerned about potentially developing an infection. For example is a mouthwash harmful or helpful? What foods to avoid? Any other signs to watch out for?