You need to see a Gastroenterologist regarding this, as this is their specialty. There are many things that can cause your symptoms, and with it being 8 years, I seriously doubt it's anything serious. You could try changing your diet. See what you are eating and drinking on a regular basis, remove one item and see if things improve within a week. If there is no improvement, add that back in to your diet and remove another food for a week until you see if things imporve. If they do after you have removed a certain food, then you know what the culprit is. Good luck and take care.
Welcome to the gastroenterology community! Have you seen a doctor about this? Have you had any testing done? Have you tried dietary changes like increasing your fiber intake?