Weird pulse in back of head

this is beginning to really puzzle me. Everytime I get up after sitting eg from this computer, out of the car when I get to work, up from my desk etc I immediately get a thump thump pulse in the back of my head…like a headache but not a headache. It is accompanied by slight disequilibrium and light headedness but generally eases off as I am upright. FYI I was diagnosed with MAV in Dec 07 at the National Neurology Hospital in London, but was also diagnosed with basilar type migraine in March this year at their migraine clinic. Subsequently my neurotologist has doubted the latter diagnosis as I do not display any of the dramatic symptoms of basilar migraine and infact I rarely get a migraine headache (three in a year maybe). So I am left with the MAV diagnosis. I have symptoms every day, generaly light-headedness/woozy/helium head and sensations of my legs being separated from my body when I do any long walks, my eyes feel sore and tired and even as though they are half closed. During the last 2.5 years various ways of coping have been suggested…topiramate (failed…depression/suicidal thoghts), lamotragine (nausea, no change), osetopathy (cured marshmallow legs but nothing else), cranial osteopathy (nothing…suggested could be my trigeminal nerve and the result of a crap dental visit), acupuncture (did cure one bad headache once, but otherwise relaxing only), CBT (good to talk, but not slving anything), increasing exercise (run/jog 3 x a week but it’s getting harder not easier), reducing my thyroxine medication level (GP thought I was over prescribed…dropped it, went into hypo, still trying to pick up again), drinking more water before going to work (duh. suggestion by Migraine Clinic in London. no difference), migraine diet (stuck to it for a while, but also trying to control IBS and left me with few choices for food. Now living off tins of mackerel in brine for mid-day meal).

Nothing has made any difference…maybe only time. any other ideas anybody? (Have had two MRIs, battery of balance and hearing tests).

I also get this. It is like someone is thumping me in the back of the head. It happens especially if my BP is up. I also have severe rocking and daily headaches with occasional migraines with auras. My BP is all over the place though. I will go thru periods where it is 110/60 and then a few weeks later it stays at 140/96. When it is low I get black outs and when it is high my rocking us almost unbearable. It stinks! I feel like the thumping has something to do with BP.