Try going to see a podiatrist - I've lost 4 nails through having a 'funny' running style - , that was put down to the way I walk (I supernate!). Now I have orthotics fitted for my problem & I don't have any problems at all. Most people have one foot larger than the other, so maybe you need to look at your shoes too. If you go to the podiatrist, take your running shoes with you, so that he/she can see what's going on. Good luck.