You're bang on about the different causes, some people don't understand that and would tell you to do a Liver Flush or something else equally stupid.
Anyway my lips are from trauma as well, and look very similar to yours if I leave them.
What I've been doing is putting on a light layer of Aquaphor once in a while when I feel I need it. All in all I don't worry about my lips anymore, they look and feel normal.