Debbie- I would suspect that the knee pain is related to the inner thigh trouble you have had. I really think the quad is shortened-which will pull at both ends of the insertion points (the inner thigh and knee). Let's see if I can help you until you can get that book. Is the pain right in the middle of your knee or toward one side (inner or outer knee) or above the knee slightly? If it's right in the center of the knee or toward the side, then it's a quad issue (do some quad stretching and foam rolling there-really taking your time over the tender spots and holding pressure on those areas for about 20 sec. IF the pain is above the knee and runs the length of your leg, it is more than likely a problem with your inner thigh. Therefore, foam roll that area (despite how dirty it looks

) and stretch your inner thighs-long holds for each stretch. Also, to strengthen that area, squeeze a rubber ball between your legs (like the thigh master). The book recommends seated leg extension (without weight) to strengthen the quad.
For the stretch of the inner thigh, it recommends laying on your back with one leg hanging off the side of the bed or table. Bring the other knee to your chest and hold. Also, I would spend some time on the hip flexors, as a seated job can cause those to shorten over time.
Also, did you see the link for the other book? I wonder if that one is on the nook? It looks like either one would be a great investment, and the second link seemed to have more info that the first.
I hope that helps some.....
ETA: Teddy-good for you for saying something to the lady who coughed in your face......really, do people not know the germ theory by now?