Go see a doctor ASAP!!!. About a month ago son complained of pain in his left knee. We thought that he just needed rest. Pain would not go away. Then we thought he had osgood schlatters disease. All the reserach we did on OSD said rest. He continued to rest. Pain did not go away and began to get worse. We FINALLY went to the doctor and a MRI later the cause of his pain was discovered. Two small tears in is meniscus in his left knee. He had arthroscopic surgery to repair the tears. He will be out for 3 months, but will be ready for his spring season in HS. We should have gone to the doctor sooner saved him about a month of pain and saved mom and dad a month of worry and trying to diagnose son's pain. Go to the Doctor and get and get an opinion. Good luck.