Thanks everyone!!! Good advice 
RicF - what's wrong with Gangnam Style?
The thing I love about runners is the willingness - nay, eagerness - to be gross. Black toenails. Ja, I've had a few of them from sprinting down hills in Cumbria 

What Gerry Alexis describes seems to be pretty much the same as mine. Don't think it's worth seeing my GP. I live in one of the worst boroughs in the UK and as a result only have access to a GP who shuts for about 4 hours in the middle of every day and gives out prescriptions like candy without even looking me in the eye. Thankfully I don't have to go often!
I did it about 4 weeks ago and it REALLY hurt at the time but I was able to walk on it straightaway. I started running again a few days ago and cycling. Interestingly the only time it has really twinged since I started training again was at the traffic lights when I had to twist out of the cleats on my road bike 
Edited: 03/12/2012 at 01:01