First, was math difficult for you in high school as well? Or is this a new problem?
Regardless, here is my advice:
- Find a good tutor. You really don't want to have to retake the class.
- Contact the disability resource center at your university. You might have a learning disability related to math, which would explain a disparity between your skills in math and other subjects. Anyone can have a learning disability, regardless of intelligence. If tests reveal an issue, the resource center may be able to help you get accommodations, tutors, and note-takers.
- It could be that you don't have a disability, but that you missed critical pieces of math instruction earlier, making it difficult to build on the (missing) foundations. Again, a good tutor might help you identify these areas and remedy them.