Hello. I Have Been Feeling Very Tense/nervous And Have Been

Hello. I have been feeling very tense/nervous and have been having trouble going to sleep lately. Today I was taking a very important exam when my heart began to race. I was sweating, shaking and it was hard to breath. My mouth became very dry too. This lasted about 10 minutes but then came in waves that lasted a few seconds afterward. As of now, I am still feeling very anxious and tense. What is wrong with me?