There have been many articles and cases about neurontin (also known as Gabapentin) as it's often prescribed for anxiety but really is not meant for that (it's practically a placebo). For me, just the action of taking a pill made my mouth water, so maybe that's what you're missing and that's what is causing the panic attacks? I was also a benzo & opiate addict (I was on benzo's for 6 years straight) and if you did not taper off them correctly you most likely will experience anxiety/panic attacks just from the typical withdrawl. I still experience panic attacks, as well as nocturnal anxiety attacks, even though I haven't used benzo's daily for a while - just minor slip ups heh
The best way to treat anxiety is cognitive therapy and exercise routines/relaxation/meditation, medicating anxiety only prolongs it and works for the short term, IMO.