Docs

And we have to go to the doctors s'afternoon and tell him that I am feeling lightheaded/dizzy when I get up/lie down too quickly

Right. Dr listened, took loadsa tests, took more tests, said "Erm...." and then basically told me I seem healthier than he has seen me, wait and see. get back in touch if it gets worse but just wait and see, he hopes it will get better by itself