Fell on my rt knee on concrete a few days ago. its painful swollen and bruised. i can still walk on it. should i give it a few more days or get xrayed

Wait another week: But you will need to consult an orthopod if it gets worse or the pain becomes unbearable.

Not particularly: The knee cap/bones are rather tolerant of simple trauma with the soft tissue receiving the main effects. A physical exam would be more appropriate than an x-ray. If the doc decided an X-ray would likely find a problem it might be worthwhile but studies like an MRI might be better if it were truly a troublesome knee.If you can go through most of your daily activities & improve day to day I'd wait