Why do I get a runners stitch AFTER I run?

I’ve never known one to last a day. You can usually make it go away by slowing down to a walk and taking deep and even breathes. I use to get it all the time till I learned to control my breathing when running. Don’t know why that was but it worked.
You probably bruised something or you have trapped gas.
You may want to check with a doctor.

runners stich is a buildup of lactic acid in your accessory muscles of respiration (your side muscles). A stitch should not last this long. Are you sure it’s not gas? If it does not get better, I would seriously suggest you go to see a doctor to make sure it’s not something beneath the musculature.

Although I have never personally experienced this, my best advice to you as a fellow runner would be to make sure you do a little cool down jog/walk at the end of your run, and when you’re walking take deep breaths in and out through your nose.

If not then yes, a doctor may be your best bet!

Thanks for your answers! I did a little research and I think I figured out that I am running too soon after eating. Oops.