How To Treat Spots With Pus In It Causing Itchiness On Leg?

i get these sopts on my legs like bitses some itch and some dont some have a white pus in them. when they pop they are like crators. then they start to hurt. some are the size of a pincle lead orthers get as big and a pincel eraser.they leak out a yellow tint liqued. i get 1 to 2 at a time and only when im sleeping.