Dave, my foot seems quite a bit better now -
I did no running for a week, stuck to cycling to keep me fit, alternated between heat and ice on my foot, rolled a golfball under my arch a couple of times a day and used a foam roller both down and across my calves to break up any tight/knotted muscle. Alot of messing around but it seems to have done to trick - About 70% better now
It's the same boring old advice that worked the most though. Rest, ie no running
How are you getting on with your foot?