Suggest Remedy For Pain In The Knee Post Injury

my knee has been hurting for a couple weeks now every since I turned it the wrong way. previously I was in accident and hurt same knee. it been fine since the accident I recently was playing around and now everytime I bend it roll on it or even sleep and that side it been pain I could bend it for a while and it takes while to bend it back it hurts should I go to emergency room what can I do.?