You don't mention the trigger that brought on the panic attack but just in case you overlooked the obvious I'll mention coffee. Excessive coffee especially on an empty stomach brings on anxiety attacks in many people myself included. If your in a stressful situation or environment the effect may be magnified. Here is a short article you could read on coffee's effect that mirrors the conditions you described. http://www.medicinenet.com/script/main/art.asp?articlekey=50... I wish you the best.