What Causes Itching All Over The Body?

i have had recurring itching in most parts of my body for at least the last two months. It is affecting my sleep and I have just got up having unsuccessfully tried to sleep tonight (the current time here in Britain is 04.39). No creams or moisturisers have any impact and, in any case, there is no dryness of even redness in the areas I can see, so perhaps it is not a skin problem.The most severe and long-lasting bouts occur across my mid-back , across my abdomen or down the outer sides of my lower legs. However itching also occurs in my upper arms, shoulders, ankles, upper back, under my ribs, my eyes , scalp. The strange thing, to me, is that both left and right sides are affected , with alternating frequencies. I had to wait three weeks to see my GP ( appt. last Wednesday ) who has referred me for blood tests which were completed last Friday. Unless something untoward is revealed (and in my experience all my blood tests have previously proved normal ) then I have to wait until the end of April for another appt. Do you have any ideas, please? Valerie