What Causes Disorientation, Constant Tiredness And Nausea?

hello, I am 30 years old 5ft and 140lbs and for years I have had strange feelings like feeling off balance. Like alot of the strange feeling seemes to be focused in the area of my head like my sinuses and my eyes feel tired all the time, and i have plenty of rest . I also feel tired alot. I sometimes feel nausia for a day and then it goes away. I have seen a doctor for thyroid and for sinus infections and I am normal. I am at a loss, I dont want to feel ill everyday anymore.