Nausea and Diziness. Come out normal. }

I have been facing continuous fatigue, dyspnea and tachycardia since 5 years and since 15 days I have been having additional symptoms like  Nausea, Loss of Appetite, Profound lethargy with blood pressure around 95-100/80, pulse rate is 100-115(resting). I did some tests and my bicarbonate serum came out to be 18, while sodium and potassium are in normal ranges.My glucose levels have decreased from 98(fasting, taken in Feb) to 84(not fasting, taken recently) even though I haven't been on diet or anything. I have eaten medicines like topiramate, biohomin, amigaba LS (prescribed by a general physician and neurologist) as I had headache issues, still having headache issues even after eating meds. I am very worried about my health, please help. {EEG, PFT, echo cardiogram, lipid profile, chest x Ray, ultrasound has been done and have come out normal.}