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...