Why is my best friend being so hostile lately?

Whenever I bring this up she just tells me it's becuase i bother her becuase I'm rude.Eversince she got a new job all she ever talks about is her new work friends and how she wants to hangout with so many of them,and tells me stories of how fun they are.If I mention people at school I've met she'll give me a dirty look that says "what are you bragging?".When I want to have fun with her all she does is give me a dirty look of "your being an idiot" and tells me I'm bothering her, while she always tells me how she acts like a complete idiot with her wrk friends(at work).She has always said nursing was her dream,but when I got pamphlets for her from the nursing department she didn't want me to give them to her and hung up the phone(her parents would pay for school if she decided to go).She got angry when I said I was so proud of an extremely obese clmate I started seeing at the gym(my friends not fat).