Help please

I think I am going insane. Not the fangirl kind of insane but really really insane as in psychologically challenged this time. I cannot even think anything properly for each second without worrying over something that is actually nothing. I do not know why but I think maybe it is because of exam pressure. I cannot even study last minute with a peaceful mind anymore. It is like the things I read are not forcing into my head the way I wanted. And I feel restless before I go to bed. Why is it happening now? I have never been this stressful in my entire life. What had happened to the carefree-go-lucky old me? This is weird. I am so confused and depressed. I could not relax at all. Maybe I am pushing myself too hard but then again since when have I started pushing myself?! Just now, I tried easing my worries by doing 8 rounds of Sudoku in succession but to an apparent no avail. How the hell am I going to sit for Biology papers tomorrow when I am so not prepared not to mention my mind is in a total mess?

This feeling... It is so painful to want to cry because your pride just would not let you.