Pain

I thought it,
Over in my head,
A lot,
Until,
I finally,
Understood.
When you fell,
And scraped,
Your knee,
There was a,
Stinging pain,
In my knee.
When you jabbed,
A toothbrush,
On the top of your mouth,
The roof of my mouth,
Was aching.
What is it?
Then I finally got it;
YOUR PAIN,
IS,
MY PAIN.