@lola1967, has the nausea caused you to reduce your fluid intake? Dehydration could explain the tired/weak feeling. Another possibility, that an internist will check for, is an under active thyroid. Neither of these are good explanations for all of your symptoms, though. Sometimes there’s more than one thing going on, for example when something like gastritis makes you nauseated, and then you get symptoms of dehydration because of reduced fluid intake.