Along Time Ago On My Calf It Randomly Got Really

Along time ago on my calf it randomly got really big and hung full of pus in this one spot like 5 minutes later I put it in the warm water and it just started draining out of a hole on my leg. I went to carenow and they didn't know what it was spider nothing so I left it the way it was. It's just a scar now do you know?