i am a female, i have brown spots on my back, inner thighs, back of my knees, and sort of on my stomach . they are slighty raised above my skin. i had them when i was about ten, they whent away after a while, now i am 19 and they have come back much worse, and it has been over a year since they have come back and are getting much worse. some times if i rub on them they get a little lighter. what could they be