I'll share my story quickly again: I had sudden and mysterious calf pain, which I had checked out. It turned out to be related to a disc problem in my back (I'll skip all the details). At that point, I had an x-ray, and when that didn't show enough, I paid for an MRI out of pocket at the university, which set me back for awhile. I went to the university, rather than a chiro or someone else who needed to pay the rent.
I wanted to know exactly what was wrong so that I wouldn't cause further damage with incorrect therapies! Now that I know what's going on and likely to happen, I can research and make more informed decisions.
When other people say similar things -- new condition, never had it before -- I suggest getting an accurate diagnosis and then going from there. Extreme "Experiments" could cause further damage (gentle things as Summer suggested won't hurt). Older knees can have several things go wrong with them. Some conditions respond well to home treatments and others will need more serious intervention.
Herbs and supplements can certainly help and may even help one avoid surgery in some cases! But you've got to know exactly what's happening, first, and that's hard to know just from a thread on the Internet. (:
In any case, I hope that you feel a whole series of fast twitches and then the knee unbends and all is well! I do acupressure on myself and that's what happens when I get knots and am able to release them, but the causes of my problems differ from yours, I suspect.
For acupressure, there are a number of books around and probably free information online. I started it by getting chair massages at the mall for $15 and paying attention to what the therapist was doing. (No WISECRACKS . . .it's in public) and now can better help myself for some problems.