Injured juvenile Robin... NEED Help.

So yesterday my 11yr old son found a injured Juvenile Robin in your backyard. It seems to have hit the top of its head as their is a visible sore.its head is just sorta limp, it can turning it while supported but the bird is unable to hold it up its self. and took some game bird feed turned it into mash as well as some sewit (sp) Not thinking it would make it though the night we put it in a large card board box with some old towels, i managed to get it to drink a few drops of water from a eye dropper and told my son that its in the lords hands. Well the little bird made it though the night and im not sure what els to do for it. we dont have an avian vet any where within 100 miles of us. so any additional advice any of you have would be welcome.