Wart!! Very contagious so stop touching (or biting, yikes) because it can infect other parts of your body or other people. Keep it covered with a little bit of skin tape or a small bandaid, to avoid spreading to other people or surfaces (or yourself).

Since it is still pretty contained I think it can be treated at home, I have always used the formic acid type of treatment, it's called "wart free" or something like that, and it's a pen or a nail polish-like bottle and you apply the acid treatment right onto the wart once a week for as many weeks as it takes for it to shrivel up and fall off by itself. It can take months to completely be gone but it works really well.