My 11 Yr Old Son Bruised His Knee Last Week

My 11 yr old son bruised his knee last week in his football game. He has not used crutches for the last 4 days,and is showing good signs of progress. He is not running yet ,and the doctor does not want him to engage in any sports for two weeks ,which will be 9/27th. He is telling me that he feels some cramps in his knee area ,I am just wondering if it a residual effect at this time ,and will hopefully heal?