Not sure why it took you so long to decide to heed the advice to see a doctor but I also don't understand what could be causing you to think it is a torn ligament. You would know if you tore a knee ligament. It sucks. And knees are not 10% as bad as shoulders. I had my shoulder reconstructed at 28 and it took 18 months of rehab to be able to lift my arm above my head.
Why so bad?
Because I tore my labrum playing baseball in college and ignored it. For seven years. So everything got effed up royally for seven years and had to be rebuilt. Had I gone to the doctor then, recovery from the arthroscopic repair would have been 3-4 months.
Well, you can tear a ligament in a knee and not know. It all depends to what degree you sprain it. Sometimes no worse than a simple twisted ankle which icing and taking care of it for a few days will help heal. It's more when the pain doesn't subside after a week or 2 that it's a serious problem. No one told him to wait 7 years to get it checked out and I don't think that was his plan.