Feeling "off"?

Sy
I've seen some posts in the past how some women have just felt "off" the day they went into labor. Has this happened to you? Is there anyway you can describe it better when you say you felt "off"? 
Here's my thing. I had awful contractions last night but they went away while I slept. Today I'm just feeling nauseated, mentally "fuzzy", and so tired. I'm not sick, I haven't gotten a fever, I just don't feel right. Sound familiar?