Could my son possibly be suffering from some sort of Seizure?

Throughout the years my son has been diagnosed with ADHD, Sensory Integration Disorder, Oppositional Defiance Disorder, has learning disabilities, yet very intelligent. When he was a baby, he was diagnosed as having "Breath Holding Syndrome" of which lasted for about 2 and a half years. He was not actually holding his breath, when he would get hurt and cry hard, he was unable to take a breath and sometimes he would pass out before he was able to take a breath. At the age of 6 docs tried saying that he was borderline BiPolar but held off on that diagnosis. He was put on Adderall (adderrall) and then taken off of it when it was realized that it was actually intensifying the negative behaviors and moods. He is now 15 years old and whenever he feels threatened emotionally or physically he gets aggressive and starts yelling obseniities and threats. Very rarely does he actually end up in a physical confrontation with anyone.  He doesnt want to be like this but seems as though he really doesn't have much control over this reaction. He recently has been experiencing memory loss about simple everyday things. For example, I asked him what he had for dinner and couldn't rmember for anything, he had to ask someone else. It had only been about an hour or so since dinner. He gets confused about who he supposed to call on any given evening. He takes turns calling between me and his father. He is currently in a program.
When he was little and going through the breath holding stuff, the ER had done a quick EEG on him but never found anything. Nobody ever actually did any sort of VEEG or MRI or CT scan. I am just curious if I should suspect that he struggles with these things due to seizures. He also used to complain about de' ja' vu type feelings.
My daughter was diagnosed as having absence seizures and partial complex seizures, and through my research on seizures, I have read about seizures that can present themselves as behavior issues such as these and be misdiagnosed as ADHD, and Sensory Integration Disorder and such!