BIPOLAR QUESTION??????????

I really think my friend is Bi-Polar. A lot of people at are school thinks that she is. Sometimes she is nice and then a real *****. Sometimes she thinks that she is better than everyone and then sometimes she's in a bad mood. She smokes MARY JANE, maybe it's to help it i dont know? I don't think she takes Medication for the disorder. Does she need to really that badly???? Will it get worse if it goes untreated?