What can be giving me abdominal pain?

A-to-Z. Ben-i would have an easier time guessing your birthdate! there are so many different diseases that can cause abdominal pain, many minor, some serious. Doctors are like "disease detectives": we search for clues based upon your symptoms, physical examination, lab and x-ray results, etc., to reach our "educated guesses". I suggest you make an appointment with a primary care doctor to determine this.
Many things. Infection, tumors, allergies, adhesions, non-infectios inflammations, vascular insufficiency, food poisoning, irritable bowel syndrome, lead poisoning, constipation, some foods, metabolic and electrolyte abnormalities etc can cause pain. You need to provide more information about the type of pain, location, relation to food and bowel movement, fever, things that relieve pain etc.