Meniscus tear?

[PolSciRunner]

Hello,
So I run a lot for a college cross-country team, usually around 50-60 miles a week. One week I did not have a race so I decided to jump my training up to 80 miles for that week. After doing it my leg started having some problems and soon enough when I would start a workout my knee felt extremely unstable and like it could not maintain my body weight. I thought it kind of felt like I was running on one strong leg and one stilt leg. I ran like this for a week, then took 2 days off, and then ran my last 5 mile race. Since then, I have not ran in three weeks, however, each time I try to start a jog I can't because it feels unstable. I can't hop on the afflicted leg either. When I went to see a doctor he thought it might be a meniscus tear and he advised me to go get an X-Ray. It doesn't hurt unless I run on it or after I run on it and when I went through some flexibility motions with my leg at the doctors I felt no pain.
Could this be a meniscus tear? I ran all my miles on the road or a canalside as well, so there was definitely some impact.

[eFitz]

something similar happened to me when i was running cross country. It started out as a dull pain and when i kept running on it, grew in intensity. In the offseason, i took up polevaulting, and never got my knee check out by a doctor. One day, I jumped on it, and it just popped out and back in. It was the greatest pain i have ever experienced. The doctor took an X-ray that showed my torn meniscus, and i had orthoscopic surgery a week later. His diagnosis was that the muscles on one side of my knee were just wearning down, so when a lot of pressure was continually being placed on my knee, it had a tendency to want to pop out to the side with the weaker muscles. He went in and tightened up the muscles on that side, and sewed my meniscus back up, and got all the fluid that had built up out of my knee. It was a very painful experience for a while, but my knee is a lot better. My advice would be to get it checked out and get an X-ray, cause even though it might seem like no big deal right now, if you keep working it that hard, it could deteriorate fast, with very painful consequences!!