What was the actual 'medicine' that cured Amir Shakkar's rheumatism, and how did his internal state contrast with his external circumstances?

The true medicine for Amir Shakkar's rheumatism was his absolute faith in Sai Baba's word. Chapter 22 clarifies that while his external conditions in the damp, cold, and filthy Chavadi were contrary to healing, his internal state was one of 'certain faith.' Baba's firm words were his only prescription, instructing him not to be concerned with the wind, rain, or dampness. By accepting Baba's instruction as the ultimate medicine and staying happily despite the immense hardship, his faith became the catalyst for his healing over the nine-month stay.