Cinder had a spot on her lip like that when she ran into something and skinned her lips. (When I say things like this about her it really is hard to believe just how clever she is because it sounds pretty stupid, I know. lol) Is it a raw spot? It healed and turned black again.
If it's raised or a lump I have no idea, because it looks too big an area to be an ingrown hair/whisker.