If you can, go to a doctor yourself and then ask your parents to go back with you and meet with the doctor. He/she will explain what is happening to you in an impersonal, non judgemental way. Your parents should not feel threatened . They can ask questions and the doctor can reassure them that they are not the cause of any problems you may have. The doctor may say many of the things you want to say to your parents but they will believe it more coming from the doctor. Don't be afraid. You have to take care of yourself. Who knows? Maybe the doctor will say you just need a small change in your life and you will be OK. That at least will make you feel better.