I have been hearing a voice in my head for a few years now

I think that there's something wrong with my head and I have no idea what to do.

I'm currently 16 and have been hearing a voice in my head for a few years now. I don't feel any emotional attachment to anyone and most of the time don't feel at all. The only time I do feel is when I'm scared, in pain or hurting others which causes an intense rush of excitement.

I never had any real friends growing up and often spent much of my time isolated ( pitty me :D ). I feel psychotic at times and often find myself laughing for no apparent reason. I know there's something wrong with my head but the voice won't let me see a doctor