Robin fledgeling, mostly feathered, injured leg

We found a baby Robin about four days ago and we need to know what do to do give him further care until a rehab specialist in our area contacts us.

I was not able to help two other babies that had perished by the time I found them, but this little guy was still alive. I do not know what happened. One was found expired behind our barn (didn't look like it was attacked), another found smooshed on the road and this guy somehow got into the barn behind our door.

When I found him he was not moving much, very weak and was opening his mouth begging for food. Dehydrated for sure. He was not able to use his right leg at all. It was pulled up to his body, the muscle tone gone and larger toe all the way open and stiff.

We put him in chicken starter and he is soing super. Weight and energy back fully, peeping for food all of the time and even his leg and toe are moving a bit again, but not as well as I had hoped.

I fed him some flys today as well and gave him some very small grit, but not sure what else to feed him. He has feathers everywhere but his head.

Please give me instruction as to what he is supposed to be eating and a rehab schedule if posible please. I doubt they will contact me any time soon and I want to keep this baby alive and well.

Thank you,
Alayne