I have had allergy problems and about a month ago what seems to be a flap of skin, perhaps something else? began moving back and forth with my breathing in one of my nostrils. It does not hurt, but is annoying and, to some degree, interferes with unimpeded breathing through my nose. It is up a ways, but I can see it. It appears white in color. Is that skin or could it be mucus that is dried and attached inside?