i dont know why but sometimes i'll get a little white bump (the skin around it will be red like i've scratched it but i havent) that comes up on my face for no reason. it looks like the white bump you get when an ant bites you but i dont get bit by anything when i get them. it'll happen randomly and it'll go away in less than an hour. what is this and what can i do to prevent it from happening cause its embarrassing when it does happen?