Awww, now see at the risk of being in the minority, I can see the kids side in this (sorry!)
The ball came your way, they politely asked you to kick it back, not only did you not do it, you ignored 'em!
They kicked it at you, i bet they didn't mean to hurt you, its just kids being kids- they dont get consequences.
I'm sure when your necks better, you'll shrug this off and see it for what it was- kids being kids ie, little gits!
PS
I really do hope it gets better soon :-)