Please do some reading on pregnancy toxemia, hypocalcaemia and ketosis. I doubt it was the long labor, so much as the need for CMPK, that caused your doe to pass.
I had read about toxemia, and was prepared for that. I thought I had all the nutritional bases covered with a goat protein/mineral tub from TSC which also contains calcium and loose minerals out all the time. The thing is she never quit being alert until she died and she never quit eating. I gave her a treat after the last one was delivered. The vet and I both thought that she was going to be fine when I hung up with her.
I am SO sorry to read about your losses, but am glad that the doeling is doing well. In this day and age, one can never be too prepared or overstocked with emergency supplies.