Thanks for the replies. When i went to the dermatologist he said that it was possibley a RARE form of urticaria and gave me the fenofexadine to try. He said there was no point booking another appointment as there is nothing more they can do. I guess from reading the forum that its true that there is no cure

and that its more trial and error to see what helps.
The strange thing for me is that it happens more in the summer, looks like for most its happens in the winter. The fact that its cold now is a relief, in the summer when the sun is shinning my body temp rises and i get this prickly heat sensation - which is the start of it happening and becomes very uncomfortable.
One thing i noticed for myself is it i stop doing exercise and put on a bit of wieght i actaully get it worse. Im guessing with the extra fat the body heats up a lot more quickly and its a lot worse. Also like with a lot of people once you sweat it out you feel better.
Is it ture that it may have something to do with the hardness of the water? Im thinking of putting a watrer filter in to soften it.