You do not mention if you have examined his feet. Is there any difference in the position of the feet (e.g. arches, varus /valgus) when you compare left with right. How long has he had the problem was there a sudden onset? Have you checked his walking, shoes. How long has he used his running shoes. Have you checked the mobility of the proximal syndesmosis between tibia and fibula, compare left with right.
And last but not least as mentioned before: you have to check thoroughly the back by 3 dimentional testing, overpressure and deep palpation para vertebral from mid thoracic to S1. By the way if anyone over 40 claims to have no history of back pain, you might well doubt what he/ she tells you during the interview.