My girlfriend has diagnosed bipolar. Occasionally (maybe once every other week), usually when she's upset, she'll start acting very different. Not normal she's upset different, but like she's a completely different person. She has totally different opinions on a lot of really big issues, it seems like what she wants out of life is completely different, and she does things she would never normally do. This usually doesn't last long (1 to 2 hours) and then she's completely back to normal. When she's normal again she says she can't tell when she switches, she thinks she's being totally normal, but when she switches back she realizes her thought processes were completely different and it feels like another person was in her head.

About a week ago she switched medications to Depakote. Since she started, she's been acting like the other version of herself all the time.

Is what I'm describing bipolar? And if it is, what do I do?