Every now and then, my left knee swells up a bit. There is no pain when it swells, but I can feel some pressure when I bend my knees (still no pain, however). It goes away within 1-2 days, and once took 3 days.
I thought it was because of physical activity that might cause extra fluid to somehow build up there. But I can recall a few times where I did no physical activity all day (except walk around, but mostly sedentary) and still got swelling in my knee. I don't remember my right knee ever swelling, I believe it's always been the left one.
And I've never had an injury on either of my knees. I've broken/sprained my left ankle, but never the knee. My mom has rheumatoid arthritis and has recently been diagnosed with gout (I mention it because it might be hereditary). I've read the symptoms on both these diseases, along with other possible causes for knee swelling (infection, physical injury, disease, etc) but they all describe symptoms of pain (and sometimes redness). I never feel pain, just minor swelling.
I've researched online and came up with nothing. Any ideas?