Burn or bruise?

[Xanadu]

I woke up one morning and saw that Xanadu has a blackish grey spot on his upper back, it's been there for about 2-3 weeks now, and is getting better, but VERY slowly. I know when Chameleons get bruises they take a long time to heal.
He's just about finished shedding, expect for that spot and his 'knees" seem to have a little bit of grey on them as well.
My picture isn't the best, it looks light but it's slightly darker in person.
Should I take him to a vet, or can it possibly go away on his own?
I have his UVB on for 12 hours a day and I also give him calcium dusted crickets and worms, they're gut loaded. He's been eating fine, other than losing his appetite from shedding, but it's getting back to normal.

Lemme know what you think

 

[TreyLcham]

Kinda looks like he is shedding. but under the shed i do see what looks like a burn not really sure

 

[NHenn]

Hard to tell from the pictures because of his shed. Do you have any current pictures?

If I had to guess a burn, but hard to tell.

 

[Xanadu]

here's a better picture, i just took it. you can see how there's a dark spot and underneath the shedding skin there's some too.

 

[nightanole]

Looks like a burn. Lizard skin heals incredibly slow. Ive seen bites and burns take 18 months to scar over and be fully healed.