I hurt my knee last yr hitting it on concrete and have constant pain around knee and soft puffy knot on outside, what could this be?

Get Evaluated. The only way to know what is going on is to get evaluated to get a correct diagnosis and treatment.
Knee pain. Because you are having symptoms from your fall that was some time ago, you should see an orthopedist. They will be able to evaluate and diagnose your condition and decrease your pain.