My mother has upper central abdominal pain, and we don't know what it is. Maybe ulcer pain?

Ulcer vs. heart. Women often experience heart pain different than men, and the pain needs to be evaluated to be sure it's not her heart. Then her doctor can consider ulcers vs. Other abdominal causes of pain in that area. If it's brand new, call 911 or at least go to er.
See doc. Really need more info to help-- could be anything at this point from gastritis/ulcer disease, reflux, to gallbladder disease, to pancreatitis, to malignancy. Best bet is to see your family doc, give a thorough history, get a good physical and go from there.