Help with six week old puppy?

I work for a kennel and we realized that there was a feral dog running around but before we could catch her, she had puppies. Most of the litter died except for two and by the time we caught her and had her spayed the two feral puppies had run off. Recently they came back and we noticed that the female was lactating but we had not seen any puppies. Last night as we were leaving work we found one of the puppies by a fence,loaded with ticks and very skinny, but the mother was no where around. I took him to the vet where I also work to have him checked out and was told that he is six weeks old. I am crating him at night and trying to socialize him until he is old enough to be put into the homeward hound program but he cries constantly. I have tried a stuffed animal and a thing that simulates a heartbeat but it is not working. Does anyone have any tips? Before anyone says release him or just get rid of him, I am trying to keep the pet population down not contribute to it so please don't be rude.