Hi. Have you had blood work--thorough testing for possible causes for your problem? Are you saying that your doctor has absolutely no idea what's going on?
Have you had an MRI of the knee or the other joints?
OK. Here are my thoughts. I would check your thyroid function, cortisol levels, do a screen for autoimmune disorders like lupus and rheumatoid arthritis, and I'd get MRI's of your joints. While this may not be just one thing, it sounds to me as though you probably have a thyroid problem and possibly rheumatoid arthiritis, given the joint cysts. I think you need to see a rhematologist where you live and here's a link for that.