Glad it's gotten better. Your school should have a bullying policy. This is something the school should be aware of and be dealing with. If it's happening on the way too and from school then it's probably happening during school.

I agree with others who've said that you need to teach Ethan to stand up for himself. Bullies only do what they do because they like the power. So you need to role play with Ethan what he can say to take away their power. A friend of mine also had success sending her son to Tae Kwan do classes. he feels much more confident to stand up for himself and isn't bothered by bullies anymore.

Being bullied can change your child. It took my dd until the end of year seven to get over being bullied in PP/Yr1. Don't let people tell you to forget/ignore it. I'm glad you stood up for Ethan and I bet he is too