Stress fracture in the middle of the left tibia. Had been through a rough period of sickness and patchy training when my leg felt awkward during a hilly run and there was a dull ache (which felt like it was coming from inside the bone). The ache would be present from time to time during walking.
Aqua jogging was brilliant and helped me maintain an excellent level of fitness throughout the period when I couldn't run. I came back and felt that my running was stronger than ever.
I am still a bit puzzled as to the cause of this injury... I think it was a combination of worn-out shoes, a lack of consistency in my training and general stress. I think I need to monitor the state of my shins by palpation because I didn't have pain in my shins when running leading up to the injury. So I can't use that as a warning sign.
I have also changed the type of shoes I wear and may need to think about orthotics in the future.