It could be chronic gallbladder problems, ulcers developing, or Celiac disease or other bowel disturbance. You should not go to the hospital unless you have a fever and pain that is unrelieved by change of position or bowel movements or eating, etc; something that suggests it needs surgical treatment. See your primary care doctor or a gastroenterologist.
Could be anything, including IBS, My own experience has been to have pain in the upper left quadrant versus the lower left quadrant on occasion.
The pain could be caused by any number of things! I suggest seeing your doctor