Ash's skull structure is worrying me

This is kind of scaring me.
I was feeling around this general area,
In the picture (Sorry it sucks) The two red ovals are what I'm talking about. If you feel on your bunny, you would understand what I'm talking about.
The bone on the right feels indented while the left seems perfectly fine.
I felt this before.
I don't know how he got it. And I don't know if it's bothering; hes had it for a while.

I'm getting kind of worried its hurting him. Any suggestions on what this might be? What should I do?

The yellow is just a representation of where his eyes are.

I would say if it hasn't changed in a long time, it could be an old injury/ something that happened in utero- and shouldn't cause pain. There are some sinuses there- maybe one just didn't form right? If they are changing, I'd go to the vet for an x-ray and medical help.