why am putting distance between myself and others?

I'll start with few things I know about myself right now: I try to be as nice, considerate and helpful as possible. I do stuff friends do, except not recently. I noticed that I've become more grumpy, more quiet, then ignore them when they greet me. I've always been like this at home, but I barely show this side of me to others, and it's not that "I'm just getting comfortable around them" stuff, it's not. I feel awful and I'm worried.

What I'm more worried about though, is that, I've reached the point where I would intentionally avoid them. Normally, I'd take the bus to school with my friend, given that our house are really close. But now, I will either wake up extra early, or extra late (even skipping my first subject) just to be able to take the bus alone, and same when going home. I don't answer calls, don't reply to texts, and been skipping school just for some time alone.

It's not them, they didn't do anything wrong, it's me. Am I scared to get too close? I don't want anyone to feel bad or worry about it so I talked to her, I told her I'm just thinking about some stuff right now-- and it's true. It's not major stuff, mostly about myself. I've been one hell of a hater of myself lately. I don't understand myself anymore as much as I used to, and that scares me. I feel like I'm not the person I wanted to be. I'm losing motivation, I haven't been as responsible as I was before, and I don't get excited over stuff I used to be excited about anymore. There are people I can relate to, but not connect. There's no one I can connect with, and that thought alone feels lonely.

Ah, really, anyone wanna bet what's wrong with me?