Is this girl on the smaller size? I to am handraising a litter of 5. They are all weaned and doing fine. What a Job! Anyway the lil boy in this litter needed feeding more frequently than the others. He went Hypoglycemic on me.
Try giving her some Nutristat or Nutrical. if it works she probaly needs to be fed more often than the others. If it doesn't seem to help, call your vet.
Good Luck and Good Job!