Yes, the cave maze brings pains... But pain gives way to pleasure eventually...
Once you've entered the storage room with the key, there's a visible object you will need there. Did you collect it?
You shouldn't need to check every tile to find objects except for when searching WITH the flashlight for a lost items in the trees at one point in the game. The rest of the time objects will either be visible themselves or within other visible objects (i.e. a crate).