For years I've been getting itchy/sore spots on my feet and sometimes hands. They're pimple-sized and usually filled with clear liquid. Occasionally (mostly in summer) I get ones filled with yellow pus on my feet, like today. Does anyone know what this might be? I am well-impressed I've gone all day without popping it it doesn't pop usually, but it feels like a pin prick when I press on it or wear shoes. All suggestions welcome!