Posture problem, affecting daily routine.?

[Zwei]

I think I got an improper alignment of backbone. As how I look something's really wrong, my neck looks too long and my head is positioned a little forward, my shoulder is a bit forward, and my lower chest pushed backward, and it's not really good to look at. I can't focus to what I do because it gives me an exhausted feelig just from sitting, and it's really hard to focus study, I feel often headaches, and I feel pain from my back and other parts of my body especially in my upper butt bone. And Im just wondering how did it become like this, what can I do, and can it be still become normal??