It's so difficult to know what to do, I know. I tried a bunch of things which just seemed to make things worse. Have you tried the constant moisture method with aquaphor? When my EC was milder I could control it and not experience any lip issues if I applied aquaphor or Vaseline about 15 times daily. If I left my lips without product in them they would develop dry skin patches similar to the ones you are describing and a thin layer of dead skin in the middle of my upper and lower lip. I didn't realise I had EC back then. I just thought I had dry lip skin from accutane. Now, I have really severe EC because I had a lip filler and everything went to hell with my lips. If I had really chapped lips before, it could take two weeks for it to normalise again. The goal is to not allow your lips to get dry for any period of time, even like 10 minutes, In my experience no lip balm is as effective as aquaphor. But now I can't use it because the crusting is really severe and it just causes the skin to peel and become really raw.
I recently bought a humidifier as well and that seems to help a tiny bit.