It was melanoma. He let a spot on his cheek go too long. Got it removed and never told us anything of it. A few months later, he got super sick and died within a few days. Turns out he knew it was coming and never told us. It was pretty fucked up, but I've come to terms with the fact that people deal with shit in their own way and don't really owe it to anyone else on how they deal with it.