Does anyone know how/where this withered heart is? I'm going crazy trying to figure out where to find it. I feel as though I've thoroughly searched all the passageways you can get to from the rotating bell platform but found nothing. I noticed a lit brazier on the floor near the ancient one's face, is there something I need to light on fire that I'm just missing?

Edit*
I just noticed that I picked up a key that opens the door in the hall that leads to the the bell platform. Whoops!

If your at the part I think you are... you have to stand on the circle next to the open dark pit area. Then there should be a blue flame looking thing that comes from the ground and the bell in front of you. Use your bow or crossbow to shot the bell and the platform moves you there. Then chamber is on the opposite side of the pit.

u get the key by going to the right with the bells. then u go back and there is a door which u open and inside is the heart