I think my girlfriend may be bipolar?!

My girlfriend and I have been dating for a month. We met online and spend a LOT of time talking on the phone, about 60 hours since we started dating. I am madly in love with her. She is everything I have ever looked for and could ever hope for in a girl. Tonight we were talking and she was acting really hyper, as in talking fast and singing all the time and just being really weird (well weirder than usual, we're both weird). Then all of the sudden she asked me how to tell these two guys who still like her that she doesn't like them anymore. After we talked about it for a little while it was obvious to me she was very sad about this. I kept pressing how this topic came up hoping to get to the root of the problem but she said she didn't want to say. After this she got very quite and would only answer anything I asked with one or two word answers. This went on for half an hour until she told me she had to go. I told her that I loved her and that if she to talk to me at anytime during the night I would be here for her. She then started to cry and told me that she loved me and good bye then said "It's over" and hung up. I waited for about 10 minutes to see if she would call and she didn't. So I called her 3 times at about 5-10 minutes and left a message on the last one about how I loved her and hope she didn't mean what I thought she did. She then messaged me about 20 minutes after that we are still together. So is she bipolar? She doesn't think she is, but has thought about it before. If she is what can we do? She lives halfway across the country. And if not bipolarity what else might it be?