Hello. I have some issues regarding lycanthropy and vampirism.

So I finished the main Dawnguard quest, had Serana make me into vampire to get into Soul Cairn, then at the end I changed her back to human. The problem is now I want to get back to Soul Cairn to finish the quest (help Jiub), but I cant since she cant turn me into a vampire and I cant contract vampirism because I have lycanthropy (100% resistance to diseases) and I cant cure lycanthropy because I didnt do it the first time in a mission and now I cant activate the flames when I go to Ysgramor's Tomb, also no dialogue option with Vilkas or any of the Companion members.

Cant find the solution anywhere. At this point im considering just deleting the quest through console even though I already have 6/10 pages.

And I apologize for making this my first thread, but it's quite a specific problem that I haven't found the answer to.

Edit: If it helps, im level 53 with all DLCs. Ugh Skyrim has a lot of bugs