Then you suddenly notice that you've getting bigger! You turn and flee, realising that dragons can get very big and the tunnels will be too small for you.
As you pass the junction you burst out of your clothes but you keep running. You continue growing and go onto all fours. The tunnel gets smaller and narrower and you start squeezing and squeezing with all your might.
Then you see the mouth and with a final burst of energy burst out of the cave - or at least the top half of you does! Your fire-filled belly is too big to fit through the mouth! You're stuck fast!