You feel like you are suffocating. You hit a wall and you can't go back.

Panic is eating you from the inside out. You can't breathe and your hot.

You can't tell what direction is up or down. The walls are closing in on you...

...You never understand what happened, nor what's happening...

Anxiety: a feeling of worry, nervousness, or unease, typically about an imminent event or something with an uncertain outcome.