I mainly stumbled into it because of a couple of mods. 😅 I started the game near Windhelm instead of Whiterun, and I also have a mod that brings a few extra dungeons to the game. I think that vampire cave was one of them, but not totally sure, it's been a while since I last played this game. 😅
Was so lucky there was a Cure Disease potion in that cave. xD xD I'm not a fan of the vampire mechanics.
Skyrim mods are amazing. Adding new dungeons sounds like fun. It's interesting that people loved the game so much they started adding extra stuff and a lot of it are high-quality additions. The vampire monster form was a little gross-looking from what I remember but there was just something majestic or noble about turning into a werewolf. Made hunting deer more exhilarating lol