PinkPwincesh, I think you should explain how you feel to your Mum and ask her to make an appointment for you to see the Doctor.
You could actually make the appointment yourself without you parents knowing, but I wouldn't advise going behind your parents back unless absolutely necessary, you still have the right to patient confidentiality from your Doctor, Meaning the Doctor cannot inform your parents about this.
I think you need to see a Doctor if you have had this rash for that long.
Try talking to your Mum first.