Not the wound theory again. It's an old theory newbies usually suggest. All I can say is the majority of EC cases are due to the drug accutane, which is proven to cause intestine damage and food allergies from that damage. Some people with celiac disease get these lips, but not most (so I wonder if it is due to which part of intestine is damaged or more overgrowth of bad bacteria which celiac disease is known to cause along with the drug accutane). And celiac disease is proven to cause intestine damage. So, I think there may be connection on the inside for these reasons. Chinese medicine also links lips problems with intestines.
You need to think about how you could chew off skin on your lips unless there was some hanging...meaning you already had a dry lip problem.