Depression?

I've been in a funk ever since returning from Idaho. I don't know the cause, but I find myself lapsing in responsibility. I can't get motivated to do anything, not even dance. I begin to wonder if I am even capable of doing anything outside of a minimum-wage retail market. All my attempts at securing employment in new ventures have escaped me. Have I wasted my chance at attaining sufficient income to pay for school, by looking for something that pays a little more? I have not played my time here well. Each day gets harder and harder to not ask myself, "why bother?" I have stressed myself to the point of physical illness, and near constant headaches (something I rarely used to get). I can't shake this fear that next year--in 5 years, even--I'll be at the same place, doing the same thing. Depressing.