How To Get Rid Of Burn Mark Under Eye?

I put toothpaste on a pimple because I read on the internet that it makes them go away. I missed the part where it can burn your skin if left on for too long. So now I have, what I believe to be, a small burn on my skin right under my eye. It's dark and feels dry. How do I get rid of this? It's very irritating because I can't cover it up, and I'm giving it time but it won't go away! Please help!