So I just went for a followup to my derm.
My EC started after a dental surgery I had.
They did a patch test for normal allergies and dental allergies and everything came up negative.
So I went back to my derm today to see what he thinks. He says since everything came up negative it's most likely just the trauma etc from the surger that caused this.
He advises to: Act normal, leave it alone, and put whatever on my lips will make it feel better, and avoid whatever makes it feel worse. He said wet/dry cycles can irritate it more, but drinking normally from a glass instead of a straw is fine.

So basically...leave it alone method? He said he has seen it before and it has taken a while to go away but it did eventually go away...