my son just had arthroscopic surgery last wednesday. his knee was swollen and would make a sound when he bent it. the pain would come and go. he told the coach (he's a freshman in college) and they sent him to an orthopedic the next day. He had meniscus tears. the doctor told him that if he continued to play baseball and not have it taken care of he could eventually have ACL problems. get it checked a.s.a.p. The recovery is pretty quick.