it could be a seizure. The EEG is like an EKG, its only good for the 30 minutes they're recording you. I would get with your neurologist and see if they can do a longer one, (there's a name but I can't remember, surprise surprise). You go in and they hook you up with the electrodes and wrap your head and you have it for usually 3 full days. The machine is portable and usually goes in a backpack. You also get a journal and a "panic" button to signal to the reader when you start to feel tingly and you can tell them what you're doing, eating, etc. I went to school for EEG and you'd be surprised at the wide range of seizures. Sometimes the activity is coming from so deep in your brain that a regular EEG can't record it.