Sounds like you're suffering from an anxiety attack. While aniracetam interacts with receptors for dopamine, serotonin, and acetylcholine (
http://www.ncbi.nlm....pubmed/11412837), these effects in themselves are fairly mild. In any of the multitude of studies performed, including long-term studies, there has never been a reported case of negative side-effects necessitating termination of aniracetam supplementation. There have also been studies specifically targeted at determining whether or not supplementing with the various racetams could lead to dependency (including this one concerning aniracetam specifically:
http://www.ncbi.nlm..../pubmed/3570103), and these resulted in negative findings - no addiction, no withdrawal.
However, assuming you're a person already prone to anxiety (as I assume you are), then taking aniracetam to reduce anxiety, then suddenly halting supplementation and returning to your pre-supplementation level of anxiety could certainly make you feel panicked. I suggest either stocking up on aniracetam and keeping a consistent supply to avoid lapses in dosage, or staying off of aniracetam once you adjust to the lack of its anti-anxiety effects. If you still have some aniracetam, you could also try taking small doses of it to taper off.
All this being said, if I had to render a judgment, I would say that this issue was not caused by aniracetam nor the lack thereof, but by an underlying issue of anxiety, unrelated to supplementation.