Have you considered strength training? It sounds like you have endurance nailed, but you need to increase your physical strength required for the shorter distances - all over muscular strength is important but I would focus on core muscles (abs, lower back), legs (all over including glutes) and also some shoulder work.
I have recently started getting feet of stone about 2-3 miles into a run. My left foot seems to tighten around the toe ligaments and the arch and then this spreads to the lower leg - seems worse at the front of the leg. This leads me to run without any push off power as I cant raise my foot properly during the stride, so I end up running with static feet! I must look like Ronald MacDonald!!!
I have tried loosening laces and no socks, which worked for a couple of runs before it came back. I have a normal foot plant with no supination of excessive pronation.
Some interesting points here, I dont like the BMI - probably because I dont do well :)
I enjoy weight training (a lot) as well as running, so my weight and BMI is skewed by my muscle weight. I have a 33" waist at 5'10" - not too bad I thought but my bmi had me in the slightly obese category:((((
I also use bfat% monitor scales - biggest waste (waist?) od money ever. It i just too hydration dependant.
Tnx for the generous support. I have been thinking of a 10K in January, this gives me some more time to train. I have planned a target of sub 50mins its just a case of finding a good course I guess. I do keep a book, but I find it hard knowing the exact distance of some of my courses (the 4.2m was measured in my car).
I eventally want to do a 1/2marathon in under 1h:30mins - but this is a long way off.