Hi sammo440 - just come across your post...

I was thinking saphenous nerve as well...i have helped a lot of chronic knee pain with a good L/S, hip and knee assessment.

Saphenous nerve (see here for a nice pic...http://www.karate.butsu.net/anatomy/827.gif) runs down the inside of the leg and very near the MCL with branches to the infrapatella area as well.

Feel between your VMO and adductors - is it more tender than the other side? If so, just try to massage it there and then see how your knee pain goes.

Also, don't forget to check your whole lower back.

See how you go...cheers.