I recently hit my right knee cap on a tailgate of a truck. About 3-4 days ago. It has been sore, but as of yesterday, the lower leg down to my ankle has began to swell. Any suggestions?

Go to your doctor, or ER.

I vote doctor or even ER. Swelling means bad things are happening.

I say go to the ER. You never know what is going on with swelling.