Interesting article on Lifehacker today for the runners among us: “What Causes Side Pain When You Run (and How to Prevent It)”.
According to the explanation provided this side pain has to do with some internal muscle strain and organs bumping around while running. How to deal with it ? Of course don’t run after heavy meals, and when it occurs take a break, and ensure your are sufficiently hydrated.
I usually don’t have that problem but I learned a different technique how to avoid and treat that problem, and I am not sure though how this is related to the explanations given in that article: breath in through your nose, and breath out through your mouth. It definitely works for me.