Past few weeks I have had problems with my stomach after eating like nausea diarrhea and cramps. Also head aches during the day. What could this be should I see a doctor?

Nausea diarrhea pain. May be gastritis with or without H pylori (a bacteria, Could be gallbladder as well or pancreatic insufficiency (rare unless you have cystic fibrosis or chronic alcohol) or food intolerances- dairy gluten soy. Keep food diary try ranitidine / prevecid once a day f/u with doc/ urgent care.