Swelling around the knee. Please advice!

I suffered pain around my right knee 4 days back , it swelled and caused pain , i was unable to walk .  There was no jerk no accident nothing . Doctor after examining says there is blood around the knee which can be due to some internal tear . I have taken medicine and  gets relief and can walk easily in just two days .  However i was feeling light pressure or weakness around my both knees from last 10 months .  So i  Gone to  Another doctor for consultancy , he feels that may be my leg is " broken " and advised me to have an xray . Please note that i can walk and run easily , yes i do feel a bit presaure around knee area on both legs . What can be the reason of this numbness around knees and this sudden swelling / pain few days ago . Please advice