JMC,
Just curious were you having breakthrough panic while on the Celexa, or just when your doctor changed it to the Lexapro?
Benzo's help tremendously on the start up effects of SSRI's, ie Paxil, etc. glad your taking a tad klonopin with it.
IBS is common with panic disorder, or lots of times, not an official diagnosis of it, but bouts of loose bowels is a strong indicator of anxiety and stress. It helped me to prepare for the day, by taking some Immodium or something to settle down my stomach before I left.
The paxil will kick in soon, actually your past the mark of the dosage of 12.5 mg and are probably feeling better with the time period of 25mgs, just couple more weeks you will see marked improvement as the full dosage your on now to feel the full effects.
And yes, everyday is another chance. Hang in there.