Hello,
Alot of people find that they do not perform well on tests, which is disporportionate with their actual abilities. Usually on college campuses there are test centers or tutoring services available that can assist with this kind of problem. Ask her if she could find out and contact them.
Other thoughts that came to my mind:
Does your daughter have any learning disabilities or has she ever been tested for learning disabilities?
Does your daughter have any issues with depression or does she have panic attacks? Has she ever discussed her anxiety with a counselor? She may have an adjustment disorder or an anxiety disorder.
Does she frequently call you over these kinds of issues? What do you say to her? Do you think you could be encouraging a kind of codependent relationship with her?
Just some thoughts.