I too suffered from minor chronic cheilitis for a couple of years just before my crohns diagnosis. At some point it evolved into photosensitivity / sun allergy. It decided to react to UVB rays, so I have to put sunscreen on my lips and around them at all time when I go outside. If I dont, I get an extreme painful rash, eczema type. I saw 2 dermatologists including one specialized with sun reactions and nothing could help me, only cortisone creams to reduce the inflammation after sun exposure. Its been many years the cheilitis is gone now, but I still have the sun reaction if my lips are unprotected. now that summer is starting Im trying a SFP 30 for the first time in 15 years instead of a 60. So far so good (before, even 30 was not enough!). IM still hoping one day this sun reaction will be over and can go outside without stressing getting a sunburn on my lips. Have you tried protecting your lips with sunscreen and see if this could help or be sun related?
for cheilitis, hydration is one key. I put on my lips avocado nut butter and karite butter (on my body too). These are extremly rich and very helpful in the winter with the cold and dryness.