Like a side stitch? I would avoid eating/drinking too much before a run. If you do get pain, slow down so that you can inhale and exhale deeper, and apply pressure with your hand in the area it hurts. The more you run, the more you exercise that diaphragm, and the less frequent (and intense) the pain will be.
Sounds like side stitches, Let your stomach settle after eating/drinking, Slow down your pace and take deeper breaths. It's something that most people get and you just need to push yourself to continue atleast jogging through it.
As other people have said, avoid eating before exercise, as the body draws blood from the muscles around the stomach to aid in digestion, leading to the muscles around your stomach going into painful cramp.
Side stitches like everyone said, did you change your diet? It could be gas pain. The least likely possibility would probably be a hernia, it really depends on what type of pain and the exact location.
It honestly sounds like a cramp. Sharp pain in your stomach that almost feels like a piece of glass is stuck in your abdominal wall?
Some people suggest focusing on breathing through your nose, and out through mouth slowly to make the cramps go away (this helped a lot during strenuous runs in the ARMY -- but never made them go away completely). But one thing I can say, if I don't run for six months and I go out and run I usually have to quit because of a cramp before anything else. After a while I can go longer without getting cramps, and eventually not get them at all.
A lot of runners don't consume milk products because it helps reduce cramps, and having that slimy crap build up in your throat when you are running.
Potassium is also believed to help with cramps (think Banana, or Potato -- if you want to be super healthy, go with a sweet potato over a regular one).