Hi my name is Tina and my daughter and I was talking. I noticed that her bottom lip has a black discoloration that I have never seen before. She told me that it has been like this for about a week. My daughter does not drink or smoke . She uses lip balm to keep her lips most and she drinks a lot of water. She does not eat food with caffeine and she is not a coffee or tea drinker. But she says she uses lip gloss a lot. Can this be the problem because she said that the lip gloss was old.