According with your description of the pain - during walking and when you bend the knee, without instability - suggests an uncomplicated trauma of the knee which with relative rest and anti-inflammatory drugs has a good chance to improve in few weeks.
However, if you have persistent inflammation and pain along with remarkable limitation on flexion and extension associated with instability of the knee other post trauma conditions should be ruled out such as: injuries of ligaments or menisci. if this is the case the strategy would be: evaluation by your family doctor and decide about the need for some imaging studies to diagnose and treat the injury. Commonly xrays and ultrasounds of the knee would be ordered to initially assess the injury.
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