First, are you sure this is not the Adam's apple? Lol. Second, were there times it went away, and when was it? If you remember when it was gone, try repeating the same moments, ex. relaxing. Is it obvious, and could it be seen? If yes, contact a doctor. If not, think of other things to distract yourself, try watching some movies, or buying something you really like- it usually helps if it's a technology based item- PC, Laptop, Mobile Phone...etc
I hope you feel better
Again, I'm just around 13, so don't expect much on the answer!
Thanks