I randomly get small bumps on my top lip, and along the edge of my lower lip. This happens every couple days and doesn't seem to have a cause. The bumps seem to be just swollen lumps since they don't have a particular color (same color as my lips), and after a little bit of time they go away on their own. As their appearing, I can feel them developing and they make my lip feel dry and itchy. What could this be?