This is more than likely to be weak glutes and core which, I know, are really poor.
The exercises I am doing are
> clams http://youtu.be/y-s7nasg18o
> quad stretch http://youtu.be/CZBKSOtyssM
> warrior one http://youtu.be/k4qaVoAbeHM
> bridge pose http://youtu.be/6HYNo1YQsUk
There has been some improvement already as yesterday I ran 3.4 miles without issue. Sure it was slow but it was great to be running properly.
I have some ambitions for my running but right now they do not go beyond being able to run a little when I am on holiday later this month.