Panic!

I began to panic yesterday when I realised I had misunderstood an exam question while preparing a sample answer for it. Today, I am seriously panicking when I looked at past papers on macroeconomics! I thought it should be relatively easy since I had done a round of studying for it before the Easter break. But I am soooo soooooo wrong. I can't answer the question at all!!! What's wrong??? I need to calm down...deep breath...inhale, exchale...need to clear my mind...