Hello You are having nausea , tiredness , stomach pain, dizziness ( lying down or in standing position ) .All these symptoms may be due to . 1 Tension or anxiety , because all other tests are normal and don t suggest any disease . So tension is one such reason which causes such type of symptoms ( patient or person sometimes feel in off form ) 2 The next reason of such symptoms may be hyper acidity as this causes pain in the chest nausea , tiredness ( feeling of ).So avoid greasy , spicy , oily foods , also avoid chocolates , fatty foods , over eating . Take some antacid but if symptoms are severe ( nausea chest pain or burn ) , you may need drugs like proton pump inhibitors like pantacloc- D once or twice in day. 3 Vitamin D 3 deficiency don t causes such type of symptoms but causes tiredness and pain in all bones , so take Vitamin D 3 as advised your doctor. In my opinion deal as I mentioned above because tension may be the reason of such symptoms . Consult psychiatrist and get his opinion ( if no improvement with these steps as I MENTIONED). Good luck.