Oooh! I had the same exact thing! I know how you feel. It is just a blister full of water, and maybe a little pus,(which is also water). I had a metal hanger in some hot coals and was stirring them around when i turned the hanger around and touched the end that was in the coals and got a burn. it was pink at first but then it swelled up and looked exactly like your heel, (just in a different shape), and it is best just to leave it alone. trust me!
Do not pop it! It will only make it hurt worse, and not to mention that you will want to mess with it constantly.
Just let it do it's own thing.