I finished couch to 5k three weeks ago and have been running for 30 mins every other day since then. But for the last ten days or so, my knees have been hurting, at first only during runs and then stiffening up afterwards and now most of the time and they're also clicking audibly when I go up or down stairs. I aborted my run half-way through yesterday, and haven't gone today, but I really don't want to stop having got this far. Any ideas? One friend said 'just run through the pain' but that's seeming like less of a good idea...