My dad has unexplained seizures

I'm going to delve right into this. My father has never taken care of himself. From age 12 to 38 not once did he brush his teeth. Causing teeth loss, constant head aches, and gingavitis. He also is a horrid alcoholic and smokes at least two packs of cigarettes a day. He looks 50 and probably only has a life expectancy of up to that maybe even less. Now to what's going on. Our family has no history of seizures or epilepsy from either sides. Nor have I or my close relatives had experience with them. Which is why when a day after work my dad went to his room, stood by his bed talking, suddenly stopped, and let out this god awful holler that sounded like the air was brutally ripped out of his lungs. It scared the Jesus out of everyone in the house and honestly we all went into hysterics. He fell on the bed, foamed at the mouth, eyes rolled back and for a good two minutes stopped breathing. We thought he was going to die but when he finally came too that wasn't the case. He woke up completely delirious and unaware of what happened and had to constantly be reminded of what happened for at least an hour. We called 911 and the paramedics hauled him off. That was a year and a half ago. We are unable to pay for his hospital bills much less the asinine pricing for the medication prescribed to him. We're hoping to get him to a neurologist appointment next month but that's only if we can make ends meet. He was our main provider but now no jobs will take him due to the doctor only deeming him 'partially disabled' and we're still filing for disability but that alone can take years. My mother is now the main provider and only recently got a good job as manager of the cleaning department at a old folks home. We were almost homeless but we got a lucky save. More about my dad's seizures; they are completely out of the blue and at random. He never has any recollection of them or remembers them even starting he says it feels like he slept heavily and wakes up to soreness and confusion. He also has no triggers; no smell, sound, color, lights, nothing. He can be standing, sitting, or laying down and be in-depth conversation. Then suddenly it strikes randomly mid sentence into a yell. He yells, tenses, then falls and seizes. His muscles clench and spasm and his hands curl up at his chest. We described this to a doctor and did some research and all points to a grand maul seizure. Some months he will only have two, others he has up to four. He's always only had one episode, but about three months ago he had two in one night only a few minutes apart. Every time he never fails to let out that God awful yell so it's never hard to find out where he is. He is yet to have one in public or outside of the house but he never tends to venture out much anyhow. Honestly it's been overwhelmingly hard, traumatic, and depressing for our family. Especially since my eldest brother passed three years before the seizures started, my dad had lost his job, and we still mourn the loss of my little sister from many years prior to all of this. I just needed an outlet to share. Also a small hope someone might have answers or similar experience as to what's going on with my dad. Any comments about what could possibly going on are extremely helpful.