I had something that sounds very similar; a thick feeling in the head like a hangover, dizziness, blurry vision and general lethargy (my sex life suffered as well). This went on for about three months non-stop. It was hell, I couldn't work or do anything. The doctors I saw here in the UK were pretty dismissive and prescribed antibiotics, recommended lowering stress levels etc. The usual mindless, ignorant and unhelpful stuff you come to expect here. However, after some investigation I started to suspect mercury. I had started losing weight after turning vegetarian and I had the idea that the mercury leeched from my fillings and stored in my fat - along with other toxic gunk - might be getting dumped back into my blood. Anyway, a holistic dentist suggested taking a gram or two of vitamin C powder twice a day to see if it might help. It worked wonders! Within a day or two my head was *completely* back to normal and the symptoms stopped. So you might want to try some vitamin C powder as a first step. Hope this helps and good luck.