Dark patch on lizards head

Hello .
I noticed a dark patch on my lizards head yesterday. I am unsure if this is a burn, fungus, or something else. I keep her cage at 90 degrees on the hot side and 80 on the cool side.
Heres a few pictures.
I use an 18inch reptisun uvb and a night / day heat bulb.
I honestly dont remember the specific brand.
Can you suggest a good night / day heat bulb for me and a good thermometer so i can confirm the temperature is accurate? Thank you very much

It looks like the top of her head is about to shed, so I'd keep an eye on that area and see if it looks normal again after the shed is complete.

I definitely suggest removing the red bulb since that can really disorient them and cause problems. The goal of lighting is to try and simulate strong natural sunlight, so I suggest using a bright white bulb like a halogen flood light or similar for heat during the day. It should produce surface temperatures (use a digital thermometer with a probe to measure this) of around 100-105 on the basking surface and a gradient down to about 75-80 or so on the cool end of the enclosure during the day. If the temps in the enclosure stay above 65 overnight, you don't need to worry about additional heating overnight.

Your 18'' ReptiSun 10 UVB bulb is good, but it should sit about 6-8'' above the main basking area for the best results and have no plastic or mesh screen blocking the bulb's output. If you need to set it further than that, I recommend upgrading to a T5 fixture and bulb which will produce adequate UVB at around 12-14''.

Thank you, i must have been overreacting, because it went away when she shed. Thank you