The other day a small area on the back of my left hand just below the thumb started to itch. For about 7 hours, it gradually became painful, and I realized there was a pocket of pus. So I drained the pus, and the area was still inflamed, but I supposed the swelling would go down after awhile. But when I woke up the next morning, it was pus filled again, and even more of my skin was inflamed. In fact, the skin over one or two of my veins, running all the way from the wound to my shoulder, was bright red and itchy. I discovered this fifteen hours ago, and although the wound seems much better, the line of inflamed skin is as red and itchy as ever. What could have happened ?