why is xanax not working?

About 3 years ago I was prescribed klonopin for anxiety/panick attacks after my mom passed away.I moved out of state in October 2007and I started weaning myself off of klonopin and it was rough for a few months but I quit having panic attacks all together until about 4 months ago About a month ago, I ended up in the emergency room because of really bad panic attack and the ER doc prescribed me Xanax. I was taking .5 mg of xanax a day and found a physician in the town I now live in. She switched me to klonopin but I continued to have panic attacks even on the klonopin so I asked her to switch me back to xanax because it seemed to be working. But now I have been back on xanax for 5 days and it seems that within 2-3 hours after taking the xanax, I become panicky. I'm not getting the relief I was getting before and I was wondering is it because I switched medications? I was only taking the klonopin for 4 days before my doc switched me back. Also since they are very low dosages, should I try to take .5 mg of klonopin and .5 mg of xanax a day?

[toejam_muncher]

you would have to ask a doctor. are you taking any preventative meds? xanax really isn't for prevention. thats not to say you don't need it right now...but i'd talk to your doctor about a preventative med.