Going through the same thing. Severe knee pain at the tendon connection points. Runner/jumper's knee, despite not being a runner nor a jumper. Gotta work out to make it better, so I've invented a machine that adds hours on the day to account for this (and other) things I now have to do.
Don't forget stretching!!!!!!!!!!!!!
Some years ago I was in the big weight room at my local YMCA and this old guy (he was REALLY old! He had wrinkly skin all-over!) was in there. It may have been the only time I saw him, or maybe he was there a few times. Anyway, I didn't see him doing a single thing except stretch, and he was at it a long long time. Most striking was his fantastic flexibility. I can't begin to do the things he was doing. He was like a supreme yogi. I do stretch in the gym (I'm going 3x/week now), but not enough. I have to really ramp up my stretching and do way more than I do at home (which is next to nothing). I stretch before I play golf for 5 minutes or so during golf season (6 months out of the year).
They say that stretching is super important for older people. You see a lot of older people with horrible posture. Stretching can go a long way in preventing that.