Upset right now.

I feel horrible right now and I have no idea why. I woke up and had a nice day. No one bothered me or made me upset. I was feeling pretty good earlier in the week and right now I just feel horrible. I have no idea why. It's like my brain won't get out of this depressive state no matter how much I want it to. There's alot of pressure in my head and in my chest and I just feel really weak right now. I don't feel like being around anyone at all right now. I really don't feel like doing anything today.
Basically, I just feel horrible and useless right now.