My BEST friend is way different! What should i do?

she very well maybe going through a phaze as she is young still. If I were you, I'd sit her down and ask why she has changed so much. Maybe something has changed and this is the only way to express her feelings. Or maybe something is uncomfortable in her home life and she is ignoring it by acting out this way. If you were best friends and plan to be again, then talk to her..most of all, listen to what she is saying. Remind her of how you both used to be and express that you want to see that person again in her. Be there for her no matter what as her friend. If with time, she pushes you away further then it's time for you to move forward. Remember the old times and live in the new.