Eckhart Tolle teaches a wonderful technique in his audio Power of Presence, (Session 1) to practice anytime, that is a life-saver when your child (or anyone else) is acting out.
Here's how (paraphrased):
1. when the other is acting out, bring all of your attention into your body.
2. notice the objects, people, sights and sounds around you.
3. don't think.
4. when you move back into thinking, restart the exercise.
5. practice this technique as much as you can during the day so it gets easy for you.
It's not that you don't care about you child's pain, but getting upset yourself will only add to your own discomfort and to their discomfort. Doing this exercise will bring you back to your True Nature and a more neutral place to think, speak and act from.
To learn more about stress-less parenting in 15 minutes for $15: http://bit.ly/CourseRebelKidCodeQuick
For the full version: http://bit.ly/CourseRebelKidCode
Peaceful parenting...it's possible.