hm i think this isnt really grave most runners have this problems me too. running directly after eating can cause this pain if u still have it u just have to go through it balding ur fist can help

When you eat before running it means that as you run, food is being digested.
And while the food is digesting it requires energy to do so which often cause the stomach pain aka stitch. When a such occurs the best thing to do is take in deep breaths which opens up the lungs giving you more oxygen for energy. To avoid the stomach pains you should aim to run say maybe an hour after you eat. Hope this helps!