Wait. What just happened here? One minute life is normal and just plugging along, and the next minute people are on fire.
While we're trying to get a handle on the tragedy we've just witnessed, Billie Jo seems to be attempting the same thing when the doctor arrives—she feels no pain at first, just the overwhelming heat of her burns.
The doctor comes to take care of her and Ma. He examines and cleans Billie Jo's hands, and when he does, the antiseptic causes her to finally feel the pain.