I recently changed from Celexa to Wellbutrin--vainly, because of the huge weight gain on Celexa.

Hi, I've been on Wellbutrin for years and I think it can initially give you a surge of energy, which usually wears off, as you have found.  If you're having anxiety, talk to your doctor.  It may wear off in time, or you may need to take something else for the anxiety.  I use Klonopin to get to sleep at night because I have a moderate amount of anxiety.  Personally, I hope I never have to switch because there are so few side effects and doesn't make you gain weight.  Good luck.  The blahs are probably part of the depression, too, that hasn't been affected yet by the drug.  On the other hand, a lot of people get the blahs periodically.