Does the pain persist long after your runs? is the burning on the inside or outside part of your shin? You might want to google exertional compartment syndrome if the pain is on the outside, and is relieved shortly after you stop running.
So they've made the 18 - 39 time a bit tougher I see. Fair enough; 3:10 was a bit of a soft target but they probably could've given people more notice. Still, I suppose they'll fill the race easily anyway so can do what they want!
Brighton is pretty over subscribed by now; they can charge what they want as long as it sells out, which it will at that price! Agree London is a relative bargain; they could charge £100 and it would still be full every year.