Many thanks for your reply. This has been an ongoing problem, much longer than a few weeks. I had ITB problems in my right side for a long time last year after returning from a 2.5 year period of inactivity when I suffered from chronic fatigue syndrome. Physio helped me back to able to run and I started training for a marathon (I am fully recovered from the illness now). I would say that there were always underlying muscle weaknesses, but I just powered through. I was consistently getting calf problems throughout my training. Core and glute strenghtening helped me a lot with my right side, but the left side hamstring injury was a new pain (January 2012). When running it manifests as a sharp pain on the side of the knee (ITB pains), the day after my hamstring hurts and the days after mainly my calf. Relief of the pain comes temporarily from stretching my quad and also foam rolling (or rolling pin) the glute. I dont feel much tightness when walking or running in my quad, its just when stretching with i.e. a lunge that I notice a massive difference compared to the right side. Its right at the top of the quad (is it nerve related?). I haven't done much running recently so it is not a repetitive strain, there must be a muscle imbalance. I can get to about 3.5 miles until the pain kicks in. Hope this answers your questions and many thanks for getting back to me.