i have had a simialr problem, with the pain kicking in around 1 - 2miles. I have started cycling as part of a varied exercise regime, and thought that in fact this might have contributed to the problem, although i dont think this is case.
Hard work to just sit around though and rest when you want to get out!
I am not able to take my place on the Silverstone half marathon so am happy to sell this to anyone that wants it. I am not looking to make any money on this, so will happily just sell for cost to make sure its not wasted, paypal i guess is best, so please in box me if interested.