You turn and look up the hole you just slid down. Above you can hear the lizard you kicked crawling down after you. The gravel is loose, and you doubt that you'd be able to climb and fight your way past it, plus any more that might be following it down the hole. You glance briefly at the stream, but there's no guarantee that it will take you to a different chamber before you drown.
There is one other passage halfway down the chamber. You gingerly make your way through the room so as to not cause a premature collapse, but break into a run once you feel you're clear of the unstable area. You follow it for about twenty yards whereupon the passage splits in two. Both are dark and relatively featureless. Behind you, you can hear the lizard hissing.