I think this definitely could be cause by an allergen but in my case, I know mine was cause by trauma because of what I said before and the day it started I burned my lip, where the triangle is and then my top lip started peeling and then it went to my lower lip the next day. I cause so much trauma to my lips throughout the years and if you caused your lips trauma too, then you need to let it heal itself no cream on this planet with make your lips heal. If you weren't a lip biter or mouth breather then there is a good possibility it's an allergen. But if you have it because of the same reason as me then you need to let it heal itself as soon as possible because the longer you wait the longer it will take to heal