indecisive; failing; discouraged; should i continue?

I'm in my second semester of Nursing school. Coming into the program, i knew how tough it would be. I just did not know how it would challenge me & my decision to become a nurse.... First semester i passed with all A's and one B. Loads of stress but i made it through.

This semester is quite a different story. I have been struggling to keep up my grades in both Pharmacology & Med-Surg 1. For med-surg, my exam grades consisted of a B-, C, and now a D. I have one more exam to go.

I don't know what is wrong. I study for hours each and every day, take notes, rewrite notes, do multiple questions online.... but come test date, and i do horribly.

I mean, a C (77%) is the minimum for passing in my school. Although, technically i am passing...it's discouraging to see a C as a grade after all the effort i put into preparing for the exam.

The online quizzes i take, i don't do so bad on and as i read over the book & my notes, i can recite what i am reading and i actually understand what's going on. So i don't see how i am not passing the exams with a higher grade.

I'm afraid i might not pass either Pharm nor Med-Surg. Im being discouraged more and more each and every assignment, quiz, or exam because of the grades i get. I know that I WANT to be a nurse. I can SEE myself being a pediatric nurse and dedicating a year to being a missionary nurse. I don't want to give up but then again, how can i not give up when all my grades are basically telling me that i know absolutely nothing & am not fit to be a nurse?

I'm not sure what i can do or what i should do. Thinking about failing out of nursing school or dropping out hurts. But i have to face the reality of it, that i might actually not pass some of my classes this semester.

Any input would be great.

Thanks.