Exactly the same thing destroyed one of my playthroughs.
Honestly, your game has ended. Because sneaking into places, even with vampire powers,with sleeping people is nigh immpossible.
You need a insane ammount of sneak to not get seen.
My advice, delete it and become a werewolf next time or check your character every time you encounter vampires , then go to morthal and get cured in the quest if you're infected.
Vampirism is pathetic in Skyrim.
Or not, since Vampirism is one of the best things I've ever seen in Skyrim.
Vampirism + Necromage perk = Godly enchantments.
All you have to do is sneak into one of the farms around whiterun around 2am and feed on a sleeping individual, and you'll go back to stage 1 vampirism. Also, you have to remember to feed on people every now and again or else you'll go back to stage 4, so be on your toes about it. It's really a small inconvenience for an insanely badass trait.