Can malnutrition cause chills and not feeling normal I've been on brat diet for 14 days doctor said it was a stomach bug. Doctor said wait 7 days.

Take your temp. Generally the "chills" are a result of fever. If you are having fever for 14 days then you need to go in for an evaluation. If the fever is "new" it's possible that you've caught a different "bug". In any case an office visit is warranted since you are still feeling so bad.