What can I do to help my Mental Breakdown?

I just recently had a major mental breakdown. I was with my parents in the car and something happened that I got angry. I had never felt like this before. As i was listening to my IPod in the car with my parents....my heart rate began to increase dramatically. I begin to have a major headache and my body began to feel stiff. Like the blood in my body is rushing through out my body at a very high rate. Out of nowhere, it reached its climax. My face was getting stiffer and I cried like never before. As I cried, my body and head hurt to the point that i screamed in the car and my hand went up while i was sitting. I body was so stiff that i couldn't control it. I couldn't move my hand but it was up. I had no control at all. I walk of the car and kept walking till my sister came and i cried even more. My body was num for awhile. And when i manage to recover, my parents doesn't want to talk about what had happen. I can tell that they were concern but i guess they feel uncomfortably about the topic. But now i feel uneasy inside. I expereneced all of the emotion that i have been holding in for many years. And it just burst. Is there anyway that i can prevent it from happening again? I am usually the type who deal with their issue individually. I expect no one to help and choose to fight on my own. What mental workout can i do to relieve my stress.