What Causes Pain In The Pelvic Bones?

i had a baby exactly 11 months ago and it was a vaginal delivery. ever since then my vagina bones between my legs have pain. it feels like my bones are squeezing each other. my periods have never been regular since after the birth. sometimes i get them at the begginning of the month, next month is end of the month, dont have one the next month and its never been a regular period.my period is normal and light and lasts 5-7 days though. why and whats wrong with me?