Hi. Thanks for your query. Noted the history and understood your concerns. Nausea on getting up from bed and IBS like symptoms, belching may in fact be due to the following reasons: IBS as you have mentioned is irritable bowel syndrome. Colitis, intolerance to some foods or beverages. Chronic intestinal infection like tuberculosis that give gastritis symptoms too. Hence I would advise you the following: Your blood tests are already normal, add-on thyroid and liver functions if not yet done. Tests of stool for three consecutive days. CT scan of the abdomen is better than the routine ultrasonography as it gives many a findings that ultrasound can miss. Only if all the tests are normal that it can be termed as IBS. Get started on proper management in the form of a course of an antibiotic, metronidazole and probiotics. Also have a PPI like Pantoprazole and Domperidone for nausea. Further management as per the findings on clinical evaluation by a Gastroenterologist and reports of the investigations.