For about 3-4 months, my left knee has felt strange. It is not painful, but more of a stiff type of feeling. It is not really stiff though, because I can flex it just fine. It does crackle or pop nearly every time I flex it though. I was not injured, so I'm not sure what the cause is. I wish I knew how to describe how it feels better, but it is hard to explain. The feeling comes and goes. When it first started, I kept looking at my knee to see if it looked different or swollen (which it didn't), and after about a week, a bruise surfaced under my knee cap. It sometimes buckles when I walk down steps. I don't understand since I can stand on that leg, hop on it, and walk most of the time with no problem. It just seems to go through periods of weakness, then will be better for a couple days. Anyone know what this could be from?
P.S. I am a 30 yrs old.