I googled a bit and it seems like what I'm experiencing is a kind of "nihilistic delusion": "A delusion whose theme centers on the nonexistence of self or parts of self, others, or the world. A person with this type of delusion may have the false belief that the world is ending." Delusions - functioning, withdrawal, examples, person, people, brain, mood, Description

Either that, or it's real. Of course. Leaning towards real at the moment, but I have to admit I was surprised to find that my experience matches up with a kind of delusion.