Use the action/reaction patterning for this as you would any other part of your novel. Using this patterning will ensure that you move forward and don't get stuck. Your p.ov. character will go through three distinct motions (but not necessarily all three every single time)
emotion, logic, action
Emotion is an instantaneous reaction by your p.o.v character.
Logic is the either/or proposition of what to do next, bargaining.
Action speaks for itself (includes dialogue also)
You don't need all three all the time, but you must have at least one.
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Action: A scream bounced off the wet interior of the cave. Sounded like it was a thousand miles away and in the same instant just over Johnny Character's shoulder.
Reaction: (Emotional) Fear grabbed Johnny around the throat and clamped down hard. His breath came in short, damp gasps, if it could be called breathing at all. (Logic) Was that Sue Character screaming back there? Was that the voice of the girl he'd invited on this doomed trip? Sounded like her. Sounded like everyone he'd ever known. But what could he do, turn around and face whatever was behind them in the dark? Was he even capable of that kind of heroism? Hero or not he couldn't just ignore that scream, could he? He couldn't keep pushing on, knowing that one of his crew was in trouble. (action) Johnny Character balled his fists together and turned to face the darkness. He took another damp, struggling breath....
ACTION: The scream cut short. It was there and then gone. Now there was only silence and what lived in that silence.
REACTION: (Emotion) Heart beating a stampede, (action) Johnny rushed into the dark.
ACTiON: "Johnny?"
REACTION: (action) Johnny stopped dead. "Sue? Is that you?"
ACTION: "I'm hurt, Johnny. I'm hurt really bad."
REACTION: (emotion) A knife twisted in Johnny's gut and carved into the handle was a single word: guilt. (logic) What was he thinking bringing Sue along? The little head leading the big head again, sure, he knew that. But he knew the dangers too. He knew this wasn't a picnic. And now? What was he to do now? (action) "Just wait there, I'm coming," Johnny shouted, "don't move. Just keep shouting out to me."
ACTiON: The darkness shifted, growled, it was like the hot summer wind had found the interior of the tunnel and was blowing through. But this was no wind. The heat, the sound belonged to the beast.
And on and on.....
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Now you just carry on with that pattern. Action/reaction. Action/Reaction. Scene ends when it looks like there's no possible action that can be taken to get them out of the situation.
Of course, as always, YMMV.
EDIT: I didn't read the spoiler, so that's why my interpretation is vastly different, also I don't believe changing anything about your actual text would be beneficial (that's YOUR writing, don't let any bugger touch it).
EDIT 2: And if you ever find yourself running out of steam, do this little exercise.
Ask what your main character wants. Write it down in a sentence like this:
Johnny Character wants to get the crew out of the cave alive.
Then you do everything in your power to make sure that the want is denied. You'll be up and writing again in seconds.
