Four wheeler landed on knee. It's been 2 months and has a knot.?

It has been two months since the four wheeler rolled over and landed on my knee. It was really sore for 3 days then it was ok, now it gets real stiff just sitting and it does not hurt bad but it's I can constantly notice there is something there. I just now am noticing a knot on my knee, it is not tender to push. I also noticed that me my knee is feels warm and feverish sometimes. Should I go see a doctor or will it go away? or what might it be?