Hi Goosey,
Thanks for the advice! I did get my gait analysed when I bought my current shoes, but that was a while ago and I figure I've done about 450 miles since then - I've heard that's about the time to get a new pair? I do do some warm up / cool down and stretching, but probably not as much as I should be doing (I have a tendency to just leave the house and run!), so I'll find some good stretches online and try and work a bit more on my warm up and cool down. I've had a couple of sports massages in the past, but not in the last few months, so I'll pick that up again as well.
Do you reckon in the meantime that it would be okay to keep running, provided it doesn't get any worse?