Running help needed!

Did my first proper run for about three weeks tonight and had to pull up half way round in absolute agony. The front part of my foot (if you imagine where my ankle is but at the front) suddenly became really tight and it was pretty much impossible to put one foot in front of the other. I tried stretching it out but as soon as it disappeared it came back again and started to creep further up my legs.

I know it isn't my trainers, they were the same ones I was running 5km in not so long ago so it must be something else. I know there are a few running people who follow my twitter feed so hopefully they can shed some light on the problem.

If there is anyone around the Canonmills area of Edinburgh who'd be interested in running a few evenings a week, very much at beginner level, give me a shout. It would be great to get a running partner now the lighter nights are coming in.