Suggest Treatment For Cramps In Knee Joints

Hi,I am 29 years old with 50 kg weight & 5 ft height.3 months back i was walking suddenly i felt cramps on the back side of my left knee joint.pain persisted for a week & then subsided,during that painful periode once i used to masage it with warm mustered oil but pain aggravated & persisted throughout the night like throbbing pain.This pain again occured twice with same aggravating factors.Pain also aggravates when i use to walk for more than 30minutes,my knee joint becomes stiff & pain starts.Nowadays i am experiencing the same complaint again.Kindly give me some advice.Thanks!