Pain Skull, where to get it?

[Valerio80]

I know that almost all things in this game are random, but i read somewhere that you can obtain ita from a quest you receive from a friendly zombie in the swamp. I searched all the swamp, but the only friendly zombie i found is the one from wich you have to take an item for another quest, and it keeps just saying me he want human meat to eat... is it that zombie? what should i do to make him give me the quest? any other info on where to find the skull?