What Causes Headaches, Dizziness, Shivering, Cold Sweats And Stomach Cramps?

I have been having some weird symptoms lately. I am in a high stress job situation and it will only get worse in the next 3 weeks. So I need to be healthy to handle it all. My symptoms: headaches, light headed, dizziness at times, weak & shakey, cold sweats at times, and yesterday strong stomach cramps. What is this and what should i do.