Abdominal CT would be a nice place to start looking for GI problems. Stomach pain can be caused by a variety of upper GI diseases - such as GERD, ulcers, or inflammation of the upper GI tract. An upper endoscopy or upper GI series would be a good place to start looking for these diseases. If negative, an ultrasound can be considered to evaluated the gallbladder.
Regarding the pelvic area - if the CT scan is negative, you may want to consider a colonoscopy to evaluate for a number of possible causes (i.e. polyps, cancer or inflammatory bowel disease). If you are a female, a transvaginal ultrasound can be considered looking for ovarian pathology.
I would discuss these options with your personal physician.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
Medical Weblog:
kevinmd_b