What am i supposed to do?

Well i've ben having this flirt with a very nice chick! She is smart, cute, good looking and very charming. And her humor is just amazing! I'm the kind of guy, who never falls in love, but all of a sudden. It happened. We have been texting every single hour of the day for several weeks. Then one day i ask her out, and she agree. We go out for dinner, and having a good time, and afterwards we went to the cinema. I followed her home, and gave her a hug, and drove home, because i was very tired. When i got home, she had written,
We contuied writing together, on till 3 days after our date. She had to go on a trip with her class, and i said, that i hoped she would have a great trip, and i'll hope to her from her when she got back..
She didn't aswer my text at all, and didn't write the following days. So after 4 days of "silence" i wrote her, but now she is completely different. She more cold, and seem without interest. And just one week ago, she seemed very interested so now i am confused.

What to do? Cause i really like this girl, and i have been together with a lot of girls, and i never fall in love. And she have said, she kind liked me, and always have been finding me interesting. So i'm a bit confused. Help me please, im lost here. And I really don’t wanna loose her.

sorry for my bad english