since we do not know anything about you your medical history nor is there a way of examining you over the internet and ordering some diagnostic lab tests it would be impossible to blindly determine the reason(s) for your fatigue. you will need to see your medical provider to start the diagnostic work-up.
why am i so tired and exhausted all of the time? . energy levels are seriously non-existent. tired and exhausted feeling all the time. gaining weight and can't seem to get it off no matter what or how little i eat.