At this point, I do not know what it is. Started after Sunday run with dogs and/or stretching after run, can't pinpoint the exact moment. Hurts on outside and in back. Swelling. Just walking hurts but biking OK. Gets better with RICE and light movement. Making appointment.
Nothing serious, likely a pinched meniscus, no tear, though, no ligament injury but some fluid in knee. 2-3 weeks without running.