What Causes Stomach Pain During Menstrual Periods?

Good morning Dr.

Myself Anita from India. I am facing a problem regarding my periods. During my periods i frequently suffer lower stomach pain and vagina pain. Moreover when i complete my periods date after that i feel the pain that it passes by my lower stomach. For this problem i searched in the internet and met with two problems named (fibroids and cervical polyps).Please help me out regarding this problem.