My coworker and I were talking the other day about my side cramps... and she said that her abs use to cramp up... exactly where you are describing.
What was her fix? Well, she said it just went away.
I would suggest deep belly breathing when you run, making sure your breathing doesn't get too labored... and maybe rubbing on the cramp when it pops up.
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather, to skid in broadside thoroughly used-up, totally worn out, and loudly proclaiming: WOW WHAT A RIDE!!!!"