hello EsmeEsme, I'm so sorry that your daughter has been bullied at school, especially at such a young age, and obviously it's a great worry to you.
I'd also like to welcome K3t77 as well, and I believe that that the schools are taking this issue with great concern so please google this 'bullying at junior school' as well as 'strategies to respond to bullying', they are aren't big sites but they maybe able to help you.
I also believe that you should visit your doctor where they may suggest ringing Reachout and/or Headspace, these are people who are trained to talk with the younger generation and also older kids, so please give a ring even before you visit your doctor. Geoff.