After midterm breakdown. What should I do?

I had 2 midterms (physics and spanish) and a bio quiz. After my physics midterm, I felt that I had failed my 2nd midterm and now the only way to bring up my grade is with a superb grade on my final exam, so, I had a break down. But, i have a physics and a bio final on the same day, back to back. Now, I am even more stressed out. When I went home, I just broke down and cried for several minutes. What should I do? Has anyone felt like this? If you have, what was your success story?