I'm 13, think i have skin cancer!?

I have this mole on my arm i've never really paid much attention too. I was in the car and started looking at it and noticed there are black dots in it when you pinch around it plus theres one you can notice just looking at it. Sometimes i look at it and think has it got lighter? But i think i'm just a but paranoid. I'm going to mention it at the doctors tomorrow and to my mum. I'm freaking out. Its normal shape and a normal shade i've had it as long as i can remember. Theres also a mole on my thigh and i've never really looked at it due to its always covered up but i've suddenly (because i'm scared) noticed it and i'm not sure if its changed colour i can't remember what it was!?