I think I have endometriosis or primary dysmenorrhea. Does it matter which? I just want pain relief.

Yes, it does matter. Primary dysmenorrhea essentially means crampy, lower abdominal pain during menses without known disease. Endometriosis is one of a number of secondary conditions that can cause the same symptoms, including tumors, ovarian cysts, adhesions, pid, inflammatory bowel disease, irritable bowel syndrome, etc. Treatment of pain without identifying the underlying cause risks catastrophe.
Yes, it matters. Primary dysmenorrhea is the most common gynecologic problem in menstruating women. It is defined as cramping pain in the lower abdomen occurring at the onset of menstruation in the absence of identifiable pelvic disease. It must be distinguished from secondary dysmenorrhea, which refers to painful menses resulting from pelvic pathology such as endometriosis. See you gyno.