What is a side pain?

Also called a side stitch or side cramp, etc.
According to Wikipedia a side pain/stitch is an intense stabbing pain that occurs during exercise.
WebMD talks about how to avoid side pains, and if they do occur how to get rid of them. Apparently they occur during exercise and are a “result of shallow breathing, not breathing deeply from the lower lung.”
I got one tonight during spin. I know that to make it go away you should breath deeply and slowly. I did and eventually it went away.
What I am reading is that side pains usually happen to beginners. Hmmm, I still get them sometimes and I have been exercising pretty regularly for almost three years.
I wonder if my exercise-induced asthma is a contributor? Well, the WebMD article I linked to doesn’t mention that.