I have the same experiences, especially when starting an anti-depressant. I've been diagnosed as both borderline and bipolar II, and I have symptoms of both, and have experiences a lot like you describe. I've been suicidally depressed for a few months, then I started the meds 3 days ago.. bam, I feel like a different person. I don't even want to go to sleep right now even though I'm really tired and have to get up early.. I was out at a bar and I wanted to stay, but my friend wanted to leave and I didn't want to be alone, so I left, but right now I'm about to take a serious dose of Xanax so I can calm down and get to sleep. In fact my life is currently a total mess but for some reason I feel great.

Often times I look in the mirror and see a different person from one day to the next. I would venture to say I'm hypomanic right now.. sounds like you might be experiencing the same. My diagnosis from several doctors was possible bipolar.. I believe them, although I have symptoms of borderline as well.