About a year ago I went out for a run and the next morning both of my knees were swollen and even taking a step down a stair led to excruciating pain. I iced both knees and wore knee braces for about 2 weeks. Finally, the pain subsided. However, a year later my right knee is still incredibly unstable and feels extremely weak. I do not run at all and haven't do to fear it will just snap in half. I don't feel real pain the knee, but some tingling and weakness almost every day.
What could possibly be wrong?