Sorry for the late reply!
Then it should be what I proposed above, I think I got where you are. Try this and let me know x3
Go to the Third Floor (upstairs), get to the room on the left.
Check the barrels for a Tiny Key and the shelves for the Ground Floor Map. Check the map then, in the room on the right, check the chest for a Hammer. Then you'd be on your way to the endings!