Seriously, where is all of this snot coming from!?

OK, so you blow your nose again and again and again...then you've got "drainage" that is causing you to have a soar throat. Where is all of this snot coming from!? Yea, I know it sounds go gross - snot. Who came up with the word snot? I'm not sure though which word is worse snot or mucus. They both sound gross if you ask me!