Hi, Thanks for your query, an elucidate history... The cause of an non-stop nausea can be a gastritis, gastric ulcer, cancer or GERD or intestinal problems. The other causes of any general disease which can produce the extreme fatigue and nausea. Third cause is related to the Psychogenic. To get a proper diagnosis you need to undergo the following: -General Check-up by a Physician to find out the signs and advise you the further investigations and to treat the cause. -Investigations of the blood, urine -Ultrasonography and X-ray chest. -To get the symptomatic treatment -Upper GI endoscopy. -Proper treatment as per the diagnosis, once you get it. -Get an opinion of a Gastroenterologist too.