Is it possible to diagnose yourself with a concussion?
You shake your head as if it will make the impossible scenery disappear but it stubbornly stays put. You pinch yourself. It hurts but not much; you don't want to actually cause pain after all. Or maybe you do. There's a rock beside you, about the size of your palmm, you pick it up and smash it against the fingers of your other hand.
OUCH!
Stars light your vision as pain fills your fingers. That definitely hurt. A quick examination of your fingers find they still bend but are already turning purple from bruising. Now you're lost in a forest and have an injured hand. Happy?

No, I'm not convinced I'm suffering anything other than delusions.

Yes, I am thoroughly convinced that I am lost.