I am also having knee pain since 20s, but that's because I fell down before and never took care of the injury and since then it has haunted me. For me, i avoided any sports that would create major impact on my knees, especially like Jogging, or jumping jacks, anything that i know will create a lot of impact on my knees.

I focus only on swimming, fast walking if i cannot swim. Thinking to get into cycling apparently it's good for the knees! and I started taking glucosamine supplement, which really helps to elevate the pain.

yeah after that i did. but no issues though. Though it was swollen for weeks i remember after i fell down and when i went to see doctor only he asked why did i wait until so late?

But after that it always has issues near the joints. Like early arthritis or something. 

Yeah need to do MRI. But current situation I am not going hospital unless absolute necessary. So far the glucosamine pills help, and also because I have been exercising (non-impact to the knees), help to elevate the pain. Gotta build the muscles around the legs to support the knees.

20 years