I never thought I had crohns disease since I do not have loose stools. However, I have celiac disease. Dermatologists are not trained about GI issues that can affect the lips. I do not even think most GI doctors are trained since they seem clueless when I tell them I have chronic peeling lips.
I had my saliva and tongue tested for bacteria, fungus, and common viruses. All the test results came back negative, but a saliva test may not be a good indicator. I just did not want to have a biopsy.
The injections mentioned in a prior post might be helpful to get anti-bacteria or anti-fungus ointments to penetrate deeper. But I wonder if this is a secondary infection or not the main cause of peeling lips.