any of you guys doing BJJ have trouble with your knees. I had a reoccurring problem come up last night with my left knee and swelling and not being able to put weight on it. Knee felt great Monday, and Tuesday night. Last night felt great too, we were doing guard drills, i passed his guard, started back in guard, got triangled, went back in guard, passed his guard, got back in guard and realized i couldn't put any weight on my knee, it was fine all the previous times i went into guard. I didn't feel anything that could cause it to swell up, and nothing out of the ordinary happened to cause it to swell up. At the end of class it swelled up pretty big and felt like there was a good amount of fluid in there. After a hot shower i iced it down last night, took ibuprofen today and have a Icyhot wrap on it. Swellling is down but still tender and hurts when touched. You guys deal with something like this and is there anything i might be able to do to try to prevent or reduce this happening.