What Causes Heavy Period Along With Abdominal Cramps And Lower Back Pain?

Hi there wondering whats going on with my body 10 days before my lmp i had unprotected sex i started on jan 25-29 also started 3 days early normally go for 5-6 days went for 4 days it was heavy couple of days after i started having abdominal cramps and lower back pain felt like menses. Just recently i had unprotected sex on feb 2 im not due for af for 3 weeks im now having major headaches sore achy breast off and on my stomach in breast has been very itchy ive notice a lilttle indesgestion too just a little increase in apeptite what could this be?