I know your original post was in 07, so I'm sure you have found some relief by now but your symptoms are very similar to mine.
I'm 21 years old and this problem started for me in August of 09. Same issue with ear pressure/fullness, I was getting very frustrated with dizziness and just generally not feeling great because I thought I was eating a very healthy diet. After a lot of searching I finally found some relief this summer when I was told after blood tests I have several food sensitivities to things I was eating on a daily basis.
Since then I have seen someone else who has targeted the cause for food sensitivities to leaky gut syndrome/candida overgrowth in my body. Might be things worth looking into for you.
It has always given me bad anxiety, actually the foods that I am sensitive to can give me very bad anxiety when I eat them. The problem is the delayed reactions of your body to these foods so diagnosing it as such can be tough. I have had many other strange symptoms like heart palpitations, sensitivities to perfume/tobacco smoke, clogged ears, headaches, strange sensations in various parts of my body (scalp, mouth, cheeks, even arms), dizziness, fatigue, and the culmination of all of them creates a very anxious daily mindset that I am constantly worried what else might be wrong with me.
Candida overgrowth can lead to leaky gut which leads to food sensitivities and many other symptoms, just might be worth looking in to.