So the spot is getting larger over time? If so, probably not a burn but could be either a bacterial or fungal infection. Can't tell which from the pics. Antibiotic ointment could treat a bacterial infection but may not have any effect on a fungus or a virus. A vet may help diagnose what it actually is and prescribe the correct med to treat it.
If it isn't getting larger it could be a thermal burn. You can help heal it with an antibiotic ointment like Polysporin or Silvadene (ask the vet for a sample). Then, double check your basking light temps at the perch where the cham would sit and move the light farther away.