I sometimes get bad stomach pain after eating as well.
I went to the doctor and my doctor said it was just a simple indigestion and heartburn problem and he prescribed me some indigestion and heartburn medicine to take and the problem of my stomach hurting after eating went away.
So I would recommend going to the doctor especially if the stomach pain after eating continues.
If it's not caused by indigestion or heartburn then the stomach pain after eating could be caused by something else such as some chronic condition which a doctor should be able to treat.
You may also be allergic to the thing you're eating and that could be causing the pain in your stomach too.
And overeating can also cause your stomach to hurt but if you're not overeating and your stomach still hurts then you really should see a doctor to find out the true cause.