I have taken Celexa in the past and trust me, hang on in there! It takes around a week or two when the jittery feeling disappears. Been there, done that. Did your doc give you some Xanax with it? In the beginning you might suffer from more anxiety since your body gets used to be given Serotonin. Just give it a try, I promise it will get better! I felt wonderful on Celexa. You might get a dry mouth for quite some time, too, but once that it over, you will feel good, sleep well and your racing thoughts/anxiety will stop.
Just give it a chance, it needs time to work and your body needs to get adjusted.