How to help her overcome her fears?

Kate

So my girl is a very petite little thing and is so sweet and gentle, she wouldn't hurt a fly. Anyways, she's had a bit of a rough toddler time with many "accidents" at her daycare, which I believe are from kids pushing her, that resulted in two hospital visits which were pretty traumatizing for all of us. Most recently we've had two more conflicts but this time at the public playgrounds.. kids pushing her out of the way and one boy who tried to push her off a balance beam 😩 I was there to stop it thankfully but she was incredibly scared nonetheless. Now when we go to the park she is petrified of other kids hurting her. Today a boy was walking towards her and she just closed her eyes and started crying!! I tried to explain to her that she didn't need to be scared, that I'm there and to say stop if anyone tries to push her but it's not helping at all.. I feel so bad for her. Any ideas on how I can help her more?