So I got to the area in the Soul Cairn and I talked to Valerica, but I then exited the Soul Cairn and got cured of vampirism. Now I can't re-enter the Soul Cairn and complete the quest. How do I fix this? I don't want to go back to before I got cured, because I'd lose a LOT of progress, but then I don't know how to fix it. PS I'm on Xbox 360.