How did Sai Baba treat Amir Shakkar's rheumatism, and what was the nature of this 'medicine'?

According to Chapter 22, Sai Baba's remedy for Amir Shakkar's severe rheumatism was unconventional. Instead of a physical medicine, Baba's treatment was His word and command. He instructed Amir to stay steadily in the dilapidated Chavadi, a place with contrary external conditions like dampness, wind, and cold. Baba's firm words were the only "medicine" given, and he told Amir not to be concerned with the poor state of the place. Despite the external hardships, Amir accepted Baba's word as the true remedy and stayed there for nine months with internal faith, which ultimately led to everything going well.