I agree. My aunt has abscent seizures and she stays very much awake. She just stares off in space for a few minutes and then she is back and just doesn't remember it and goes on about her business. She can't drive but she's ok with that. She's been like this for many years and she barely even has them now. Some people do get de ja vu right before a seizure, I heard it was the gran mal ones though. Like the ones where people shake for a few minutes. But from what I heard, some people never get any warnings.
Either way, I don't think it's a brain tumor at all. And I really don't think it's seizures. If so, they will not kill and they can be treated.