What's going on with my body?

I haven't really been able to eat much, and I finally ate some yesterday and thought I was over what was wrong in my previous question but today I woke up and was extremely nauseous and has a headache, I took some medicine for the headache, and I tried to eat some frosted flakes because that was the only thing I felt was good at the time. I took one bite and gagged and brought to my mom and I was shaking, and still am shaking really bad. When I lay down I am fine but when I'm on my feet is when it is bad. My mouth is really dry so I stay drinking water, and the thought of eating is making me feel so sick. I also had the runs when I woke up. I'm thinking of calling into work today. What could be going on?