Could my breast hurt due to me taking the prenatal vitemens or could I actually be pregnant. Its only in my right breast.?

Possible. Prenatal vitamins do not cause breast tenderness. See your doctor or take an over the counter pregnancy test.
Breast Pain. If you think you cold be pregnant, please take a pregnancy test or call your doctor's office, it is common for young women with periods to have one sided breast pain. Usually it is due to hormones and changes to your cycle. Warm compresses and/or anti-inflammatories such as advil (ibuprofen) might help heal any discomfort. If you notice any lumps or new changes, please notify your doctor.