Progress was good over a few days, and now suddenly I've hit a problem. I've hurt, maybe sprained a muscle in, my left knee. At first it ached a little on the back inside, then within a day, started stinging at the front whenever I bent it. There's no way I can continue until it's recovered. So after a day's rest camped near Ben Alder Lodge I made my way down to Dalwhinnie for some further rest days.