As I read your message the thing that keeps coming out is that you are either exercising the muscle (making it shorter and developing yet more lactic acid in the fibers) or just resting (which doesn't force out any of the excess lactic acid).
I suggest you read this thread: viewtopic.php?f=9&t=762
to see how there are so many muscles that can be a part of your quadricep situation. You'll also see the Julstro Protocol which will show you how to self-treat each of the muscles. You'll need my book, Treat Yourself to Pain Free Living
to do the protocol, but you'll be pleased when you see how effective each of the treatments are at relieving this problem.
Wishing you well,