I am wondering if you gave mom CDT? Before we gave CDT to our kids we had many who died in a similar fashion same symptoms. Healthy a birth, though always slightly weak, took a little longer to stand/nurse....and they would appear to be nursing fine on mom though a little lack lusterly and would simply go down hill from there. Full udder on mom and the kid appears to be starving to death. We would take them inside to warm them up and milk out mom to feed them but very few ever survived even when we caught it within 48hrs of birth. I dont know why but CDT seemed to stop this.