My best friend changed over summer break and i don't like it, what should i do?

Its our freshman year and one of my best friends turned emo and i don't like it at all! i know probably sound really shallow and all but im not its just shes so different she has changed so much in 10 weeks like now shes completely obsessed with my chemical romance, mikey way, and criss angel and she dresses in all black and red and wears a brace knuckles necklace to school and she puts on lots of red and black eye make up. it scares me every time i see her and at lunch she sinks down low in her chair and listens to mcr on her ipod on full blast and won't talk to anyone, maybe im just over reacting but i don't like being seen with her its kind of embarring because i'm like completely different i wear bright cheerful colors with a ribbon in my hair and i talk to everyone no matter who they are. Okay my question is what should i do? i have lots of other friends that i can hang out with but im her only friend so i don't want her to feel lonely but what would you do or do you have any advice?