I fail my first midterm

Today is a bad day for me. I just found out that I get20.5/60 for my first CS373 midterm. This is lowest score I had ever get so far. Even though the average is not high(29-30), I am so surprised and worried when I found out about my score. I kept telling myself there must be some mistakes in grading but I feel even worse when I got back my paper. I remember I had a tough week last week. Exam...paper....programming....assignment..feeling sick.....I thought I had tried my best to sort things out but I think I was wrong. I didn't get enough sleeps nor eating enough food just to make sure that I can finish doing all those things but everything went wrong. I was supposed to rush to my East Asian Literature class but I was so keen on finish the readings for that class that I end up going late to my discussion. When I reached the classroom, I found out that everybody has started doing their weekly quizzes and all I had is less than 5 minutes to finish the quiz and I don't even get a chance to finish reading all those questions. Then, my TA reminds us of the importance of being punctual to class. I think that it is unfair because I always arrive early to class but yet arriving late once makes me the "guilty" one. Why can't she be more understanding? Maybe it is my fault after all. I was feeling so sad so I thought reading might help but I don't realize that time passed by so fast and the next thing I do is running to the class. Is there anything I can do better? I think I had devoted most of my time finishing my assignment and studying for the exams. I don't know what else to do.