Is it possible to prove epilepsy?

Hello! I will try to put a long story short.

There is a 25 y.o. man. He suffers seizures from about the age of 20, usually evening/night/morning, during which he
- falls unconscious,
- stops breathing,
- stiffens, then shakes rhythmically and violently,
after that he has some kind of a deep sleep for an hour or so. If he's woken up shortly after the seizure, he looks really sleepy and gives incorrect answers to simple questions (like, what's your name, where are you, which town is it) or just makes sounds as an answer.
He doesn't remember any seizure, but he
- feels them approaching,
- his body and head ache after them,
- he bites his tongue,
- sometimes he gets severe bruises and cuts.

And now I'm getting to the point. The man went through MRI epilepsy protocol, routine EEG, 2h sleep EEG in daytime (sorry if named incorrectly, I'm a foreigner), and these records gave nothing. Some deviations are present but not enough for a clear diagnosis. Is it even possible if he has an epilepsy? Is it possible to somehow confirm or deny epilepsy with other tests, to understand what's exactly going on? Thank you a lot for your time!