On-Going Knee Injury

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About a year ago I climbed Ben Nevis for charity and on the way down my knees took a bit of a pounding, after a few days rest I climbed another few mountains and on the way down from one I got this really sharp sharp pain, that felt really deep in the knee, It was quite agony to bend my knee and move properly..

After a few week resting the knee I returned back to the gym, my gym sessions are normally just cardio, such as the treadmill, cross trainer and the bike; after running for about 5/10 minutes my knee had that same pain again..

Now, 1 year later, the same pain is still haunting me, I can normally jog for about 10 minutes before my knee gives in and gives me a lot of pain.. After reading forums/fitness sites I tried altering my trainers and how I run, I've tried coming down onto the front of my feet and down on my heal. When coming down on my front part of my foot I can normally go a little longer but the pain eventually comes back and I have to pretty much ditch my training..

Has anyone else had this type of issue or have suggestions to what could be causing the problem? Walking is not effected

Thanks in advance