Son has to see child psychologist for bullying

My son has been back at school since the 2nd and there's this boy named Danny that my son is mean to for no reason. My son is 8 and has never been a bully but he's taken Danny's glasses, made fun of him, and has been so mean. Today my son got suspended and is now going to see a child psychologist because he pushed Danny off the climbing dome thing. I sat him down and asked why he is so mean to Danny and he said "I hate him!" I asked why and he out his face in his knees and said "Idk...." I asked why he pushed him and he said "He was playing with Michael" (some kid from his class he's not even friends with). I said he doesn't like Danny so why does he care who he plays with and he shrugged. He meets with a child psychologist Tuesday. In the mean time does anyone know what can make my son just randomly want to bully this poor boy?

Idk what he would have to be jealous of. He's not friends with Michael and the bullying was started before that.

@Sara his teacher is just as puzzled. She Saud on the first day of school during free time she saw my son draw a picture of him and Danny so she thought he would want to become friends but instead bullied him. So ig my son liked him at first and changed his mind in 2 seconds... My son is the only bully in his class... I feel like a bad parent.