I feel there is nothing I can do... Is there..?

Well what you should do is wait for a little while maybe a day or two. Then talk to her and tell her how you feel about her and why she doesn't feel the same anymore if she gives the "I can't deal with this right now" or the "I just don't know" tell her how you're willing to wait for an answer and that you care for her deeply for her. If she tells you why she changed try to understand that and try to make her change her perspective with the situation. But if she doesn't like I said tell her you're will to wait for her.