I'm about 4 days away from my period.. and my nipples are so sore.. not my breast but my nipples.. does this mean a period or pregnancy?

Neither: Nipple is not a reliable way to tell period or pregnancy. If you want to confirm pregnancy, you should use a urine pregnancy test. These tests are available over the counter at drug stores.

Hormones: Nipple tenderness is commonly associated with the increased Estradiol levels in the blood that occur during the last two weeks of each menstrual cycle. It should relieve when your period starts. If your period is late, or if you think you might be pregnant, do a home urine pregnancy test.