Yes you will need to learn the basics of chemistry. It took me two years to finally get a strong grasp for how chemical reactions take place. I got a C in both semesters of general chemistry and organic chemistry. I then had the highest grade in my biochemistry class (97 percent). All of my classmates that were in the biochemistry class all got A's and B's in general chem and organic chem. I just had a tough time grasping the concepts of ions, cations, reactions, how to do the calculations, and so forth. What came easy to me was naming a molecule, recognizing a functional group, memorizing the structure of all 20 amino acids, memorzing bond strenghts and distance between bods in a covalent bond, and why and how certain reactions take place. I even had to memorizing the structure, function, and active form of every vitamin. We also had to calculate pH, pKa, and Vm in the biochem course.
I had one classmate that always got a perfect exam score in the general and organic exams. I finally got a better exam score then this student in my biochem course because I was able to finally understand the material better then him because I have more interest in the material to do my interests in metabolic disorders. Heck, I'm now taking some graduate school courses in the sciences while he is still taking microbiology and other basic science courses and we started college at the same time.
You need to give yourself time. If you need to retake the first semester of gen chem, then you will need to retake. All you have to do is explain that you had a tough time grasping the material and wanted to do some preperation work to learn the material since you have such a strong interest and love for the sciences/medicine. You then will need to show it in your grades (upper level grades show your understanding better then general courses in my opinion).