My knee is really loose and hurts randomly. This from a football injury over a year ago. What's the problem?

I took a hit to my knee during practice about a year ago. My foot was planted and the hit came from the outside directly on the joint. I was then pushed sideways over the guy who fell on it in the resulting pile-up. The joint immediately swelled up, it hurt extremely bad and I could barely walk on it/ put any pressure on it that day. I had a lot of trouble for a couple of days making it up the stairs and lifting my leg over the lip of the shower. pain and swelling persisted for at least two months, most likely do to my continuing to practice. It hurt to bend, and to put pressure on it and the pain was sharp. I never sought medical help for stupid sports related reasons, I just sucked it up and tried to keep practicing. I got hit in the same location a second time about four months later and suffered a repeat of the symptoms except they were less severe. Finally, during wrestling season my leg was locked out during a match and again it swelled up, hurt to bend and was difficult to walk. I got an MRI that was inconclusive and it was umed I was fine, yet still today my knee is really loose and randomly becomes painful. The pain is dull and is located both inside my knee and on the inside side of my knee. What can the problem be and is it too late for treatment?