O.K , Now let me explain to you why after a long period of abeyance from panic attack you again started having them and why are the current drugs not working and what needs to be done as of now.
Since you were placed on Klonopin for many years , klonopin (clonazepam) which is a benzodiazapine , though very effective in controlling panic attacks , has a flip side like other benzodiazepines , and that is, one develops tolerance to the drug making it less effective , requiring either increase in dose or changing it with a different benzodiazepine.
For the same reason , that all benzodiazepines develop tolerance, they are given for short periods and if at all given for long duraion their dose is to be managed along with the timing of intake.
As of now, since your panic attacks have increased in frequency , despite being placed on 3 benzodiaepines -- klonopin, xanax xr , and ativan , the problem lies here itself, as instead of giving 3 benzodiazepines at the same time , your doctor should have increased the dose of klonopin to 1 mg from .5 mg and instead of giving it 3 times a day , it should have been given 2 times a day -- one at morning and second at night , while keeping you continued on cymbalta. Too many of benzodiazepines , will make you so strongly tolerant towards them , that you have no other benzodiazepine to feed upon in order to alleviate your panic attack. And that is what is happening with you right now, and is due to reduction in the dose of klonopin and sporadic use of other benzodiazepine.
So, i suggest you that as soon as your doctor comes back after vacation, you should better re work out the treatment plan , avoiding use of so many benzodiazepines, sticking to one with increased dose given two times a day along with contnued use of cymbalta.
I hope my answer serves your query according to your satisfaction.