Probably not what you want to hear but I suspect you may have injured a meniscus or ACL. You may have pushed a strain to more of a tear but my instincts tell me you should go see an orthopaedist and I am a big believer in doing everything else first. The 2nd time you injured it , did it swell fairly quickly or a lot? Did you hear a pop? What position was your knee in when you reinjured it?