Tomb glitch

IDK how to describe this. I saved in the second pig village, then tried to return to the first plateau via the Pig Tomb. All was OK, until I got to a room with pressure points. Whatever I dropped on them disappeared with a poof of smoke like the smoke at the edges of the map. After reloading, wind blew through the tomb, and the chiton seems to be floating in water, and the whole screen is black and my character icon does not appear on the map.