What Causes Chronic Dizziness, Pressure In Head And Intermittent Chest Tightness?

Dr. Rynne, I wondered if you could help me with the following issue. I have suffered from dizzyness for years. Not vertigo, just a sensation of pressure in my head, associated wtih a sensation of not quite being coordinated and not htinking clearly. I don t feel like I will fall, just that I am unstable. SOme times there is some chest tinghtness like I am panicking, and sometiems I get shakey. It comes and goes.. sometimes bad enough for me to need to lie down. I have found eliminating some foods seemed to help at least temporarily (milk and then egg). More recently I found taking an antiparasite (over the counter) seemed to eliminate the sensation dramatically for about 1 week. Later it returned following a very acidic salad (drenched in lemon juice). I wondered if it could be a reaction to reflux or something else? Thanks in advance. Chris