Week for nod complaints

A week before my period starts, I get a burning and sore feeling in my belly (pelvis/groin). It's a nagging sensation. As my period gets closer, the symptoms get worse. I have a mild form of endometriosis. I'm wondering what causes these symptoms so early in my cycle (sometimes just a few days after ovulation).
Does anyone else experience this? Did you also have this feeling and symptoms in the week leading up to when you got pregnant? Thanks in advance for responding!