I had a small scab 2mm just below knee on shin accompanied by a lump about 5cm across. I had done a lot of rigerous home repair prior to noticing this and thought I had just hit it on something. Overnight it became quite painful to touch or walk. I used heating pad on it and overnight the bump has gotten less prominent but now there is redness and tender skin up to 4 inches away from the small scab. I am concerned that this may be an infection now.