My son who is soon to be 4 years old is biting himself typically all up his arms. He is doing this hard enough that he leaves marks. When I ask him why he is doing this he said it will make me happy. I tell him that it doesnt make me happy it makes me sad that he is hurting himself he will reply with it doesn't hurt it feels good. I am not sure what I should do to make this behaviour stop. Is this a sign that there may be something wrong with my son??
Your son has unfortunately found out that self harming can cause pleasant feelings. Help him to find friends and interests instead.
This is more common for teenagers, but can occur with younger children.
Read about self-harm.