Poor Chase

Okay, so I didn't take a picture, because I don't think I could handle seeing it all the time. Chase has been having such a hard time at school lately. There is a kid in his class who is picking on him (I always thought he would do the picking). He came home three times last week saying that this kid was hitting him and pushing him down. On Thursday he came home and said that this kid had given him a bloody nose and that the teacher had tried calling me. Okay, frusterated, no call showed up on the caller ID, not sure what happened there. I immediately went to the school and talked to the teacher. He didn't know anything about this kid picking on Chase, I guess the "duty" didn't tell him anything. Anyway he has been trying to make escuses why he can't go to school, but always changes his mind when I remind him that if he doesn't go to school, he doesn't get to play with friends all day. Well, he seemed better on Friday after school, so I hoped that the teacher, who said he would talk about bullying with the whole class, had helped. Today Chase came home with a big bump and scrape down his face. He was playing soccer and this kid came up and shoved him down on the cement. I'm having a really hard time deciding what else I can do. I don't want Chase to think that I don't believe him, but sometimes he keeps changing his story. I don't know if he thinks I will get mad at him, or if he doesn't want to get into trouble for something. All I know is that today it went too far. If this kid really did push Chase down today, and it wasn't an accident, then I need to go back to the school and figure this out. How do I help Chase to tell me what really happened, and get the true story without making him think that I don't believe him. I want him to have faith in me, that I will do all that I can to protect him! I need any advise you are willing to give.