Only A Phase, Ma: A Gallery of Oddities Story

In the Gallery of Oddities hangs a particularly strange portrait. 
An ordinary summer day, no school, nothing to do, Mom's yapping and she just won't stop. Time to go find the cat.
And time to get your arm torn off by a creature in the gutter. 
But the Gallery wants more. Which means one simple injury spirals into an endless summer of strangeness. 
A portrait of a boy and his mother as only can be painted in the Gallery of Oddities.