Sudden burst of energy?

My first trimester was hell. Period. The second one I felt pretty well back to normal, and the third at the beginning I stayed super tired all the time, and when I wasn't super tired all day, I became that way around 4pm-ish. But the last week to 2 weeks I have felt great, and have been able to go and go nonstop. Doing my nesting and organizing, and cleaning. I know some women don't ever experience this, but I'm wondering from those of you who did, how long did it last? And how does it end? With labor, or with a coming down crash?!