For starters, I finish the quest to bring Serana home. Her Harkon asks me if I want to change into a vampire lord, and I respond yes.
After going through the entire tutorial of how to use the Vampire Lord powers, it tells me to go to Garan Marethi to begin the quest, but as I walk throughout the castle, everyone is telling me that I am still mortal, and that I should go see Harkon to change the problem. I return to Harkon but he is scripted to recognize me as a vampire. Everyone else in the castle absolutely does not, and I cannot grab the quest from Garan, as he continuously tells me to become a vampire again.
When I reach stage four of vampirism, everyone attacks me when I am in humanoid form, with no hesitation. The only person that does not attack me is my follower (who is Illia at this point in time).
I am unable to feed at all. Drinking Potion of Blood also does not revert me back to stage one, and has absolutely no effect on my character at all.
To top this all off, I fought vampires and it said I contracted Sanguinare Vampirism despite already being a Vampire Lord.
I'd also like to note that after accepting Harkon's gift, and becoming a vampire lord, my humanoid character form underwent no transformation at all. It didn't look like I was even a vampire, my character still looked like a normal Wood Elf.
Is there anyway possible to fix this? Uninstall/reinstall did nothing, and I'm not well versed in the console commands or which ones I would even try to input to attempt to fix this, if it is fixable at all. I have no mods other than a few vanity ones.
As of right now, the game is a bit unplayable for me since I can't get any quest, I can't reduce my stage four vampirism with anything, I can't cure it because Falion kills me on sight, and I can't progress the game at all with this. Since it's my only save file, and I have no other previous saves before becoming a vampire, the game is completely unplayable for me right now =\.