Although and since are used to describe the situations further with more clauses, they are not used to indicate the chronological order of the events. The first thing and then are however used for this since we are presented with what happened first and then with what happened after that.
I think that it would be a great idea to try as hard as she can during the exam and after the test go see a supervisor or teacher to explain what happened. Maybe she can then retake her exam or her situation can at least be taken into account while grading.
