My mother 81 years has been having these symptoms the last 2 years and are gradually getting worse : Outbreaks of acute abdominal pain , diarrhea , nausea , vomiting , black stools , weight loss , and episodes of weakness and fatigue.

Let me cut to the chase . Acute abdominal pain , black stools and weight loss may be associated with colon or stomach cancer. Black stools may be due to digested blood , which would indicate a previous problem, as in the stomach or even the esophagus. The loss of considerable amount of blood may lead to weakness and fatigue. If the cancer was large enough to (partially ) block the intestine , this could cause abdominal pain, nausea , vomiting and weight loss . Diarrhea is because feces leak around the blockage . Outbreaks of pain could be due to peristalsis (think of a snake swallowing something big and gradually moving over your body by constriction and relaxation). But when the feces reach cancer , difficult to pass , causing pain. I hate to be pessimistic but my job is to look first potential emerging / dangerous causes and then evaluate the most common causes . I can not stress this more , take your mother to your family doctor or geriatric physician. Needs to be examined . Having said that , if it ends up being cancer and choose not to perform surgery or chemotherapy, make sure you have assistance available palliative medicine. Good Luck!