What Causes Clotting Of Blood Around The Area Of Piercing?

Hi there. In December I got a fourth piercing in my ears and it kind of hit cartlidge. Well a couple days ago I found a "blood bubble" of some sort right next to the hole. I had the same thing for my third piercing and my belly button piercing a couple years ago. I kind of messed around with it which I probably should of done but I just want it gone. Any advice? Thanks!