Should i be worried about sudden death? Please help!!?

i am a 15 year old boy and my cousin died in his sleep about 8 months ago. They did an autopsy and said it was sudden arrythmic death syndrome A.K.A. SADS. It is inheritable and i am afraid that i have the disorder. They checked his little siblings but they turned out fine. They also did an EKG on me about four months ago and said that i was fine as well. The problem is, i am having the sympthoms again and i'm afraid i can have a cardiac arrest at any minute. I asked my parents to take me to the doctor but they said that i'm just having panic attacks. DO you think that i have the same disorder that my cousin had, since it was genetic? Do you think that i need to get checked out again? Is the EKG reliable?