Why was Amir Shakkar's stay in the Chavadi so difficult, and what was Baba's reasoning for making him stay there?

Amir Shakkar's stay was incredibly difficult because he suffered from rheumatism, and the Chavadi was in a deplorable state. Chapter 22 describes the place as old, dilapidated, damp, and home to scorpions, lizards, and garbage-filled holes. Amir became miserable in these conditions, but Baba's 'medicine' was simply His word. Baba firmly instructed him not to worry about the wind, rain, or dampness. By accepting Baba's command as the Great Prasad and staying there with faith for nine months, Amir's internal conviction was tested against these harsh external conditions, which was the core of Baba's trial for him.