Thanks ZHR, I've done a bit of reading now and understand a bit more about shinsplints. I think you maybe right, symptoms and the causes all add up to Tibialis posterior shin splints. Hmm...I have been running in an unbalanced manner due to the weakness in my left leg plus tramping through deep snow with a dog tucked under my arm and so a bit lopsided. Blast! Better get a really good strength and stretching regime sorted and stick with it from now on. I'll rest up a bit this week and see how things go. Am not ruling out the physio yet but want to give myself a chance to rest first as I really have upped my miles and been in tough conditions lately.