What happend to Coyotio after the doctor treated him?

Coyotito's conditioned worsened after the doctor saw him, just as the doctor intended. The powder was meant to make Coyotito sick.... it was meant to insure that Juana and Kino would be indebted.

Then from his bag he took a little bottle of white powder and a capsule
of gelatine. He filled the capsule with the powder and closed it, and
then around the first capsule he fitted a second capsule and closed it.
Then he worked very deftly. He took the baby and pinched its lower lip
until it opened its mouth. His fat fingers placed the capsule far back
on the baby's tongue, back of the point where he could spit it out, and
then from the floor he picked up the little pitcher of pulque and gave
Coyotito a drink, and it was done. He looked again at the baby's
eyeball and he pursed his lips and seemed to think.
At last he handed the baby back to Juana, and he turned to Kino. "I
think the poison will attack within the hour," he said. "The medicine
may save the baby from hurt, but I will come back in an hour. Perhaps I
am in time to save him."