I am more than my soda?

OK--day 4 with no soda and therefore no caffeine (other than the small amount from a few Hershey's kisses with cherry filling--great limited edition holiday flavor!) and I am dragging......like really slow. I'm tired and kind of cranky---I'm having to work hard to maintain an acceptable attitude.

I have considered the probable causes:

1. I'm going home for a few days?--eliminated this one, because I am actually looking forward to the trip for once. I have some work to take with me, a couple good books and I should be fine.
2. The job search stress?---well, eliminate this one as well--not really feeling the crunch yet and I think I have a good shot at several of the places I applied. My CV is in decent shape for a new grad, I have pubs and I have teaching experience with great evals, I have done some service and feel like I am really prepared to be in a tenure-track position. I am confident about interviewing well (I have as much if not more personality than most 'nerds' in my field)--I just need an interview and I am secure that something will come along, it's early in the game.
3. End of semester run down?--elimiate this one too---the end of the semester is my favorite time, I'm almost done with this group of students--just one lecture plus review day to go before I give the final exams. Then I will have several days to just work on my writing/research---I can't wait!!
4. So? --Well, it must be my new found freedom from sugar/caffiene that I was loading into my body. How many days to really get through withdrawel??

I'm really hoping that after these days of "in a funk for no reason" are followed by a new found 'high' living without all the caffeine and that I get my optimism back and stop feeling so tired. Don't want to keeping dra....gggg...iiiinnnn....ggggg.......