Why did Sai Baba make Amir Shakkar, who was suffering from rheumatism, stay in the terrible conditions of the Chavadi?

When Amir Shakkar narrated his illness of rheumatism to Sai Baba and prayed for deliverance, Baba's prescribed remedy was for him to stay steadily in the Chavadi. As detailed in Chapter 22, this place was old, dilapidated, and far from comfortable. It was inhabited by lizards and scorpions, had garbage and deep holes, and was plagued by dampness, wind, and cold. Despite these contrary external conditions, Baba's instruction was firm. The stay was a test of faith, and by accepting Baba's word as the true medicine, Amir was to find his cure. He was ordained a stay of nine months, with the company of Sai being the 'Great Prasad' that outweighed the physical hardships.