Hi I Am A 53 Year Old Female. I Have

Hi I am a 53 year old female. I have had gastric bypass, hysterectomy and a bowel obstruction. I have been experiencing left abdominal pain for a few months now. Before this if I stood up too quickly, I would experience severe pain sometimes in my groin area other time and more frequently in my left abdomen. I have been to my doctor and was told that it was the weather and I was dehydrated. Since then I have doubled my intake of fluids and am eating small amounts at a time. I am experiencing mild heartburn, which start hours after I have eaten. My left abdominal pain is still present. A urinary tract infection has been ruled out also. What should I do?