Could you tell me what this is?
I heard it could be something like a callus on the ball of the foot. Actually right under the second toe and feels like a worm. Will it go away alone?

What do you mean it feels like a worm? Is it just a callus?

What you have is called a Plantar Wart. Plantar meaning the bottom of your foot. This is a virus like a wart you may find on other parts of your body. You can find products over the counter to trat plantar warts but I would suggest seeing a podiatrist or you family physician for proper treatment. They can spread to other parts of your body or to other people.