A Hex(or) on my Flexor

I awoke on a Wednesday and something was wrong
Pain in my leg, I hope it doesn't last long
It was a struggle just to roll out of bed
My right peg was acting as if it was dead
Shuffle to the shower and try to jump in
But my day of pain was just set to begin
Unable to lift much more than an inch
Just putting on a sock would cause me to flinch
Getting into the car was also a chore
Having to lift my dead leg inside of the door
Everywhere I walked, I was forced to go slow
As I dragged my injured leg, right down to the toe
So what was the source of my infinite pain?
My hip flexor surely has a humongous strain.