I lose focus while working on something important.

i dont know why this happens, I lose focus while doing something important, very important, like when I was in college I couldnt focus while studying for exam and other time its okey I can focus. now I can work on everything with focus but when ever its something important I cant focus, my head is like its in the air, clouded and I get headache. please help me!!!
Asked May 05, 2014

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