I have this mysterious sore on my left leg. I have no idea how I got it. It doesn't hurt or itch. It's on my shin about 4 inches about my foot. The only reason I knew it was there was because someone pointed it out. I've known about it for about 4 days now. It looks like some kind of burn. It's red and recessed into the skin a few millimeters. A clear fluid is all around it. I can feel the fluid if I put my hand on the mark. It is red all around the mark and my leg is swelled from it. Also, there is a lot of heat around the mark and a lot of red that expands outward from the mark, about half an inch. The mark is oddly shaped like a kidney bean or something. Or like the state of New Jersey, flipped about 270 degrees clockwise.

Today the mark looks like it might be getting better, however, for the first time, its really starting to hurt. Any ideas what this could be?