What Causes Dark And Scaly Lips?

Hi, I m 23, Male, from the U.K. Off late my lips (upper) has turned black especially in one part of the upper lip, its turned scaly(when I feel it with my tongue. and not to mention, its slightly swollen under(lip) the blackened area. however, my lips are not chapped. I m suspecting dryness, but then again I use loads of Vaseline and almond oil. what could be the problem otherwise?