Kinda unsure of how to interpret this. The first part really does remind me of anxiety(the type I get when I show people my game and they give me radio silence to try to avoid me lol). I guess you could could explain the falling as a panic attack that makes you lose sense of your surroundings.
What I can critique is the gameplay. Wandering around in the fallen zone is kind of aimless(perhaps intentional). The enemy there as a manifestation of her fear. I can dig that, but the sanity loss is too sudden. Perhaps make the floor around the enemy crumble as she approaches. That makes the threat more obvious from a gameplay perspective and makes narrative sense as well.
I don't really play games like this so I don't know how to approach this lol. But I do sense potential here.