Looking for Cthulhu story...

[Eagle Prince]

I am just finishing up a mini adventure for D&D, so I was getting ready to start another one.  The idea I have for it seems kind of familiar though, so I will try to explain it and if anyone knows of another story like it please tell me, or even if it just seems familiar to you too.

Okay it goes sort of like this.  Your basic horror-made-flesh Cthulhu creature, but he is invisible... so only if you get past the invisibility will you see how horrible it is and go insane.  And this thing protects some little kid, they are like buddies and when he talks about his monster buddy, people write it off as an imaginary friend.

Well I got a lot more backstory for it, but the part that seems familar is the boy who has this invisible Cthulhu as a buddy.  If its a lot like some other story then I'll want to change it a bit.

[The Holy Saint, Grand High Poobah, Master of Monkeys, Ehlers]

it's like Sigmund the Sea Monster on PCP.

[Eagle Prince]

Sigmund is the one thought up by a drug-induced monkey.