Sounds like boys being boys. That older boy is probably upset he got into so much trouble so he's taking it out on ur son.
I am so sorry you have to go through this trauma ,is there no one you can turn to for help ,you shouldnt have to keep your child inside but maybe till this is solved you will have to , certainly the school are responsible for what happens there,children often dont tell it all for fear of retribution and also being told they are lying, so they keep quiet and the perpetrators often threaten them .You do need help and quite honestly I would be looking for somewhere else to live ... I do sympathise its a tough one and you need help with it, has he a Dad around maybe able to show some influence with these bullies, sometimes a male figure on the scene will deter the offenders.
True, I did speak with child service about 2 days after the local police was call. Now what is bothering me is that my son never told me the entire story. This was done to him a great number of time. What happen his he open up to his teacher, then his teacher call me to let me know that my son has open up to her. Regardless of the age it is still a abuse, for a child to do such thing to another child... i just wonder why is it that the have close tis case so fast. Has for the bullying it happening at home outside. it is consedered harassement. My son can't even sit on the front step without being told to go in the house that he has no right. almost getting hit with a hammer. Being trow a basketball at his head. I just believe that this boy is angry cause my son talk. For that boy mother, every time the boy see my son he tell him how much is mom hate us and want us to move out, and if my son defend himself after being hit he tell him how his mom will come to beat my child. this is so crazy
You have to seek professional advice I agree something is going on,keep your son away from the others , make sure he is supervised he is only 6 years old. What has he to say about the matter I doubt if a 6 year old was the instigator I would think an older child .I do think you need to call , speak to child services with the names of all the children involved. If this is happening at school you need to speak to the head teacher and your son's teacher it is their responsibility if bullying occurs at school... Good Luck