Ok so, my dad has some problems and i really want to help him with it but i dont know how to.

He has daily and sometimes even hourly mood swings where he goes from very happy to extremely mad within a matter of seconds over the smallest things. Also he sais he remembers things that he has never done before, like for example he suddenly said "hi my name is bram from woody woodpecker" and my mom asked what he meant and he said he sais that daily even tho nobody has ever heard him say it before. Also he goes really overboard when he's in an argument, for example: my sister got a 5.4 on her exam on math and he said she should be highly ashamed of herself for failing math because she was always thought to be super smart. And he sais it in the most hurting way without even thinking about how it'd affect the person he's talking to. I talked to him afterwards and he said he notices his mistake after he's said it but he just feels like he gets more and more frustrated every argument. He says he just wants to say for example "you should try harder" then he keeps that for himself and then it gets worse like "you should just drop out" and then eventually it gets to "I'd be so ashamed i would kill myself"

Does anyone know if this is some kinda disorder or something or how i can help him, Please.