What Causes Back Pain And Dizziness During A Menstrual Period?

Hi! I'm actually wondering if I might be pregnant; I've been experiencing a lower back pain for almost three weeks now. I always feel bloated,dizzy,and sleepy, but I'm having my period. My stomach is a bit bigger than the usual.My breasts are soft as well as my nipples which is a way different from the usual sore breast and nipples whenever I have my period.