Hello and hope you are doing well.
Sometimes migraines can cause these odd sensations without an actual headache. If you have blurring of vision, nausea and see some light flashes it could most probably be due to a migraine. Cure can be in terms of avoiding trigger factors. You can prevent the occurrence of headaches by avoiding trigger factors that induce an attack. Alcohol, smoking, altered sleep patterns, missed meals, loud sounds, odd smells, physical or emotional stress and certain additive foods are known to trigger attacks.
Hope this helped and do keep us posted.
Thank you for your comment. Please report your results and Good Luck in February.
Sorry, just re read your post and see you have had scans. I am waiting for an appointment which I should hear about by mid Feb 2013!
I am unable to help you other than empathising with you because I too, very recently have started with exactly the same symptoms. (I too fear I may have a brain tumour) Have you seen a Doctor? I also have a weakness in my lower arms and hands and a few other symptoms too.