What do i do! a baby robin needs help!?

i have a robin`s nest in the tree beside my bedroom window. one iof the babys got rejected by it`s mother and i found it on the ground in a pile of leaves. it is very weak and is barely breathing, i have it in a shoebox with a pillowcase in it. it is wrapped up pretty well in a washcloth and i have a warm light above it just enough so that it can get some extra warmth. what i have fed it was a mixture of powdered skim milk, oats, 1 crushed up tums and a bit of water to make it a kind of liquidy. i have read you are not supposed to give baby birds water or any other liquid. Did i hurt the bird or is what i`m giving it okay? also the baby bird is about 4 days old. what should i feed it? will animal services take it and help it or am i on my own? and do you expect it to live? Thank You!