I turned into a vampire and for some reason I lost the ability to feed on sleeping NPCs after a while. Whenever I approach a sleeping NPC while sneaking and hit "E", it doesn't give me an option to choose between feeding and pickpocketing, it just goes straight to pickpocketing.
Is there any way I can fix this or can I change back my character by using a code? Any help would be appreciated. Thanks in advance.

So weird. I just summoned Alva to test something. I guess the game doesn't recognise me as a vampire, although I am one. When I summoned Alva she attacked me and infected me with... whatever causes vampirism, although I'm a stage 3 vampire. So very weird.

are you running any mods? i seem to remember there is one that affects vampirism in that way.

I'm not running any mods at all. I think I may have done something to cause this though. I travelled to Japhet's Folly to check it out (after I completed the quest) and I hung around too long, and I used all my saves on that location. I couldn't fast travel out to begin with, so my only option was to "teleport" to an npc via codes. I believe this set some things back since I can repeat quests I've done in the past already.
Isn't there a code that can cure vampirism? Since the game doesn't recognise me as a vampire, I can't cure myself, and if I force the infection upon myself again it will take a while before it kicks in, so by the time I "really" become a vampire (again) I'll be a stage 4 vampire already lol.

use the console command setstage 000eafd5 10

i get this glitch a lot of times. If you are truly a vampire without mods, look at your face. You should see a vampire morphed face. If you DONT, it means your char isnt registered as a vampire, or you happen to get the vampire abilities but your race isnt changed.

Thank you! This worked. Phew.