At random times, sometimes a few times a day, sometimes a few times a week, there will be these areas on my feet that cause suddent pain while walking on them. The area will swell and its almost unbearable to walk. They usually disappear after a few minutes though. Some are flairing right now and I took a picture. Any ideas?? The one is on the back of my heal and also feel sort of itchy, the other is on the bottom of my foot, which is a more common location for them to appear.