I've been doing some self diagnosis on Google, and the most likely culprit is 'plantar fasciitis'. Plantar fasciitis is an inflammation of your plantar fascia, a strong band of tissue (like a ligament) that stretches from your heel to your middle foot bones. It supports the arch of your foot and also acts as a shock-absorber in your foot.
You can learn more about the condition here http://www.patient.co.uk/health/Plantar-Fasciitis.htm, which is where I've taken this image from (thank you www.patient.co.uk).
I found a reference that a poor gait can cause plantar fasciitis, so I started paying special attention to my foot as I walk, and I noticed that I was crunching up my right foot, pulling my big toe in and rolling my weight around the outside of my foot, whereas on my left foot I'm was rolling laterally from heel to toe and distributing the weight evenly. I also had more flexibility and control on my left foot that my right.
This is probably as a result of the very bad sprain I got which resulted in me being inspired to change my running style (or maybe I was already doing it to some degree which is why I injured myself in the first place - who knows!).
Most the treatments I found talked about stabalizing the muscle and arch using inserts or boots, or more severe cases having cortosone injections, but this didn't feel like the right answer for me. If the plantar fascia is being shortened because I'm scrunching my foot up, then surely immobilizing it will compound the problem. It seemed to me like I needed to stretch it out! Shoe inserts and corrective measures have never run true with me, and I always pestered my parents about why do we need shoes as we didn't evolve with them, and when I was a teenager I remember disagreeing with Mum about the need to wear shoes as my feet wouldn't grow properly. The result: I do have wide size 7.5's, which in my late teens and early 20's I regarded as terrible as my feet were too big for cute little stilettos, but now I'm glad that at least my feet developed as the should when I was a child.
I digress! On Saturday I had a massage, paying particular attention to my foot, Achilles and calves (as these were very tight and could have been a contributory factor to my possible plantar fasciitis), and have been going everywhere I can in my bare feet, or just socks in the office (where bare feet would definitely be frowned upon), and have been focusing on allowing my weight to be centred on the foot, allowing the arch to decompress.
For me, this has helped massively,to the extent that I went on my second barefoot run today. I can still feel some slight sensitivity in my heel as I walk, but nothing when I run due to good running form meaning the heel isn't really weight bearing. Maybe it will come back and bite me, but hopefully I'm on the mend. I'm lucky - some people with plantar fasciitis suffer terribly for many months at a time.
I have self diagnosed and treated, and if you suffer from plantar fasciitis I recommend you get a professional medical diagnosis and treatment plan. There is a lot of evidence out on the internet and in books that suggests barefoot running not only prevents plantar fasciitis, but can also be the cure for it, but then on the flip side others people have found it causes or aggrevates the condition. Everyone's different. Maybe it will work for you, but always speak to a doctor or physio therapist to check if it is safe for you to try.
