Pain on inside of right knee

I had pain on the inside of my left knee.  I do not recall any trauma that made the pain start.  It hurt when I ran / walked but did not hurt biking or swimming.  It also hurt w/ certain twisting movements.  I was taking ibuprofin and icing it down while staying off of it and decided it was OK to run a 5K on it one weekend.  About 1/2 through the dull pain I had became an accute pain.  Swelling ensued and I couldn't walk on it after the race.  I ended up tearing my medial meniscus - it's the "C" shaped cartilage that serves as the pad between the thigh bone and lower leg. 

Definately see a doctor - I saw an orthopedic surgeon who ordered an MRI on the knee and sure enough it was a pretty nasty tear.  They will also check for ligament damage.  Unfortunately other complications (DVT and persistant blood clots) delayed the surgery to remove the torn cartilage from 6/11 to 9/27. 

If it's hurting when you turn on it, it just might be that.  Hopefully it's just a sprain and you'll recover quickly.  But definately see a doctor.  Looking forward to see how it turns out!  Good Luck!

Hard as it was, I did not run until the dr appt other than 2 short, easy jogs just to check status of knee pain.  1st time I had a lot of pain, 2nd was day of appt and although there was some pain, actually just some discomfort and I felt I could have run through it.   The doc did an external exam, flexing, bending, poking and he said everything looked good.  Took an x-ray to be on the safe side and it was ok.  Told me to ease into running and come back if I experienced more pain and then maybe an MRI.

I ran that night, 4 miles easy pace, felt pretty good some soreness but no pain like before.  Ok on Sat, so ran again, this time 5 miles, still ok.  Ran on Sunday, another 5 miles, more stiffness and sore afterwards.  I realized I was not "easing" back into running, at least when coming back from an injury.  I just missed running so much it is hard not to over do it.  So now I've been running every other day or so, no more than 3 miles yet.  Some at the gym where I'll bike for about 10 minutes before getting on treadmill.  Knee seems to be doing better, a little sore at times, gets better after a little running and just a some soreness afterwards.  No sharp pain like I had experienced.    

So far the dr has not had a whole lot of value add, other than to confirm there is no structural damage and knee appears to be in good shape.  To be fair by the time I could get in to see him, I had been resting knee enough the injury seems to have healed itself.  He did not speculate on cause of pain.

Slow and easy is the comeback plan, which is common sense anyway, just can be hard to do.    

I don't think it's the shoes, one of same brands/models as I've been wearing, switched to a new pair about a month before I had any problems.   

I did some research on this and I'm not sure if this is my problem.  I really have no knee pain except when running, downhill activities don't cause pain.  I've started lifing weights and leg/knee lifts don't aggravate it.  Doc thought knee was structurally sound.   Thanks for the input.