Hi, My dad has a bump in the middle of his back, between the shoulder blades. He s in his 50 s and has had it for at least 20 years. Every month or so, he says it will get extremely itchy, and around that time, it s able to be squeezed, sort of like a pimple . It seems to be much deeper though; and the pus that comes out of it is white and smells putrid. What might it be, and is there anything that can be done at home to get rid of it?