The Case of the Mysterious Bumps

Nina: I have these mysterious bumps in my mouth. Sometimes they appear and then they disappear then they appear and then they disappear and then they appear and then they disappear and then they appear and then they disappear and then they appear and then they disappear and then they appear and then they disappear and then they appear and then they disappear.

Me: Weird.

Nina: I know. They're there and then they're not and then they're there and then they're not and then they're there and then they're not and then they're there and then they're not and then they're there and then they're not and then they're there again.

Me: What do you think is causing them?

Nina. I have no idea. They're just mysterious.