I have a new theory. Yes, we have ended up with yeast or bacteria infections. How do you get yeast infections? Moist environments like possibly drooling in sleep? I'm thinking of vaginal yeast infections that females get due to the ph level being off. They use antifungal creams to treat it. People here who used apple cider vinegar seem to have a temporary improvement in lips. Apple cider vinegar improves the ph level. Yes, the question is what is affecting the ph level. Maybe it's drool...drool that also has yeast or bacteria in it from inside mouth worsening the lips even more.
Why might you drool in your sleep? You might be a mouth breather unable to breathe through your nose.