Pain during intercourse only around my period

I have noticed only around my period that when my hubby and I have sex I get intense pelvic cramps that are so painful they leave me on the floor in the fetal position until they subside.. Unfortunately I got on webmd and it lead me to possible endometriosis... My husband and I would like to begin trying in July and I'm really concerned.. Is this normal? Do these evil pelvic cramps typically occur to other women??