it comes

why you have it on any particular day can be correlated with any number of factors. 

and the tension is building always

the flesh beneath your skin getting tight, electric

your memories getting itchy,

till you're forced to scratch like a dog suddenly jumping to flick his ear or chew his ass.

and you let your day disintegrate beneath the cloud of dander you've released. 

Arg. chew on your ass.