I had got up to week 5 and starting to really enjoy the challenge, only to be floored by really sharp pain on the outside of my left knee. It's been a few weeks now and there's been no improvement. In fact it's getting worse. I've been stretching out my glutes and piriformis and doing 'clam' exercises as recommended when I had this pain about a year ago. Could it be caused by something else? I don't really want to bother the doctor and I can't afford a physio at the moment.