not myself?

I have been told I am not myself lately. What is myself? Why does everyone think they know me so well? I think there is only one person on this earth that knows me pretty well, and lately I haven't been around them. So that leaves me to think, what is it that I am not? Is this something that is just part of my growth and change therefore I can accept it, and just expect others to accept it as well?

What is myself then and what is myself now? Sad thing is that I don't know.