I found this, which is the procedure the NHS has to follow in these cases.
It's actually quite comforting rather than worrying. Strangely
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2813642/
don't want to sound patronising but you really need to stop searching the web, you will never find the first result coming back as "youwillbefine.com", fortunately you seem to have found some good stuff too but PLEASE stop trying to self diagnose, I have been there and you will screw your head up
saw a news prog once where they said that 1 in 5 websites listed a Brain tumour as a main cause of constant headache where as the chances it was is 1 in 50,000
