I'm getting pretty paranoid... do i have skin cancer?

i am thirteen years old, about to turn fourteen. and i had a sunspot on my arm, about the size on an eraser but it turned redish and got a little irritaded. i told my mom and she said just to keep an eye on it. but recently i got a bald spot removed from my head with surgery because they said it was cancerous. i also have a mole on my back that just appered and it is also irritating because its under my bra strap. and it will not seem to disappear. so any suggestions??? THANKS <3