My first thought was a ‘thorn in my side’ so I had to steer my mind away from what felt stereotypical of “thorn”. I instead thought a thorn could also be a prickle, like the prickle of forgetfulness. The creature who reminds you that you have forgotten but not what it was. 

There's a prickle in my memory dancing with my jaw, aching like a tooth between words. It consumes my focus and begs me to remember but refuses to let me listen. Your playful words wash past me, or I past them, slippery hands unable to grasp their sound as it is flushed by this desperate prickle. Trigger happy and overpowering the pack-a-day perfume still begging me to remember, all it knew is that I forgot but its guidebook lays bare. Ink invisible or absent. Guide posts abandoned to the forest…

There was a frantic energy with this. The panic of trying to remain engaged in a conversation while the rising panic of what was forgotten steals your focus. I wonder where it could have gone to from here.