definitly if x ray shows nothing.and you have pain and instability and in some movement some jerks you feel.definetly you go for mri .and start physiotherapy rehabilitation for your knee.
Next Steps
put less pressure or weight on that leg .so further injury will not happen
Health Tips
do icepack 3 to 4 times a day .get educate about your issues well enough so you take precaitions and prevention.and can live healthy and feet sporty life ahead