I hesistate to make this post, but I will just suggest an option that I took. Do not do anything without discussing it with your GP, and only do it once. More and you're on a slippery slope.
Some years ago I had a post or two made a 'Sticky'. They were about Valium. I had a lot to say about the dangers of Benzodiazipams.sp? However, using the drug as a diagnostic tool saved my bacon when three eye surgeons failed to come up with an answer to eye pain. I asked my doctor for a small quantity of Valium and within 30 mins had the answer to weeks of pain. In this case it was spasm of the extra-ocular muscles.
The important point was that I never needed another one once I knew what was happening.
I would suggest that you obtain ONE, medium dose Valium and see what that does. You may find that it puts all your thoughts into a pleasing and relaxed order. If it does, the rest is up to you, because you will know that there is nothing seriously wrong.
I recongnise your symptoms so well, don't worry, and don't turn to drugs for more than a single test. You will have to figure out the record of such a drug being prescribed...maybe your GP would allow you one tablet from his surgery.