He should deinately see a Doctor to get the proper testing done to find out what the heck is going on. Sometimes, seizure activity can hide deep in the brain for several years (that's what happened to me) and then show up when you least expect it to.
Stress is a major trigger for a seizure, sometimes it won't show up til the next day, after there's been a stressful or traumatic experience, b/c the natural body defenses fight off a seizure but then, when the defenses are low,(like the next day) you will have a seizure.
He should not be driving until the seizure condition condition is under control.
I hope my little speach has helped you a little bit. I'm basing this on my own 26 yrs experience.
Diagnosed with epilepsy and ulcerative colitis in 1979,
Been on meds ever since.