I am 21 years old. I noticed a sort of strange yellow discolored spot of skin on my right breast, a little more than inch above my nipple. It almost looks like someone poked me with a finger and now I have a healing bruise, or like someone poked me with yellow highlighter. It has been there for over a week. It doesn't hurt even when I touch it, and I've check my breasts for lumps multiple times and found nothing. What could it be? Is it something to be worried about?