I am an avid runner (30+ miles per week) who has been dealt many set backs. Runners knee in both knees. I had an MRI on both. Went to PT and was introduced to Kinesio Tex Gold tape. This stuff is great. Make sure your knees are clean and apply it (
youtube has many videos). I am now fighting plantar fasciitis in both feet. Podiatrist, shot, custom orthotic inserts, etc. You can surely walk/run but to walk the hole thing. I hate to see anyone walk a half marathon (race) but I guess it is better than those sitting on the couch eating chips! Good luck with your knee. If it keeps up I would definitely see an orthopedic.