What is the issue here?

I am only in high school and have undergone depression for a few years now. There is this girl that I've known since middle school; she mentioned that I was the sweetest guy back then, but something changed since then. She said that she has been seeing something and it is scaring her. Sometimes when I look in the mirror I will see something; it's myself, but it isn't at the same time. I can't really describe it at all. I've isolated myself from everyone starting in high school, in a reclusive nature. I spoke to my guidance counselor and she said I am far too cynical for my age, yet, very hard to read, even coming from her. For the past few years, tragic things would happen, and what I feel is nonexistent. Most peers remember me years back in earlier school, but say something is different. I tried speaking with the one girl but she said she can't communicate with me any longer. What happened?