I’m no pro, but I had a similar ordeal. To me Looks like a burn and the skin is necrotic slightly ( being black / grey ).
I believe Silvadene would be a good thing to look into , prevents infections from burns and helps the healing process. Helped my girl immensely.
I feed greens / cricket...
Stocked up on gutloading supplies and the calcium ,
Just added a egg laying area.
( just misted hence 75 degrees, was 85)
Currently looking for a vet, gonna stop by my shop this weekend to see who they recommend.
Yes I have a Zoo med repti sun
T5 HO high output terrarium hood
14" size in size
( holds one 15 watt 12" repti sun t5 high output lamp).
Basking is about 80/85 Degrees
With humidity around 55/60%
As far as gutloading I do use spinach , kale, carrots , zucchini and other various fruits and...
I'm keeping a very close eye on him,
He still is eating and acting normal so far,
It looks like the mark is healing slightly but I did notice he's keeping his mouth open slighty today.
It is hot and humid today so I'm trying to adjust and keep him aclimayed
Your Chameleon - panther chameleon, male, and about 6 months.
Handling - Not often, once a week if that. I usually leave him be.
Feeding - depends on what I have but usually 10-15 medium sized crickets a day ( cup and free range). Horn worms as a treat, and dubia roaches when I had them.