My close female friend won't reply to my facebook messages? :(?

[Mega]

I'm a male, and I've known this girl for 2 years and we're close/best friends. We tell each other everything, etc. She told me a few days ago that I'm her best friend and stuff. But recently she hasn't been replying to my facebook messages even when it says she's been away for 5 minutes, etc. Also, at the beginning of the year, she's met a new friend that is not a very good influence on her, and I guess they've both been into guys and stuff. Anyways, at the moment like today, she hasn't really talked to me at all, etc. Do you guys know what could've possibly went wrong? She used to go on skype all the time just to express her feelings and stuff, etc. She doesn't even go on skype anymore to talk to me and it's been a few weeks.