Yellow spot on skin..

For about five years I have noticed a yellow spot on my left breast, when I first saw it about 6 years ago, getting into the shower, I thought maybe I dropped mustard down my shirt, it went away that same day and I was freaked when I saw the same exact spot, same color and size months later. There is no pain and it's not like a bruise at all.. its always the same bright yellow color and it there and then its gone, it doesn't fade.. I still see it sometimes, about two or three times a year. Could this mean a liver problem? I cant find anything about it anywhere and Im starting to think it has to mean something. Just wondering if anyone has heard of this before or knows what it is.. Oh and Im 22, female.

Thanks.