Stomach feels like someone hit it with a baseball bat. no headache, fever, fatigue or anything. how do i figure out what's wrong?

Abdominal pain: For severe abdominal pain like you describe, it is best to have an evaluation by a physician. There are many potential causes of pain, so you should have an exam, blood tests, and possibly an imaging test like an ultrasound or ct scan. Sometimes an ulcer can cause this kind of pain and won't be seen on a ct. Gallbladder problems and pancreatic problems can also cause mid-abdominal pain.