Can you tell me about the story from the Satcharitra involving a doctor from Malegaon and his nephew's illness?

Certainly. Chapter 34 of the Shri Sai Satcharitra narrates the story of a degree-holding doctor from Malegaon, in the Nashik district, whose nephew suffered from a severe bone-cyst, also known as Hadyavarn. Despite the uncle being a physician and consulting with many expert and intelligent surgeons, no remedy, whether native, foreign, or even surgical, could cure the boy's ailment. The young nephew was in constant, unbearable pain. After exhausting all medical options, the family heard about Sai Baba and the healing power of his Udi, leading them to travel to Shirdi as a last resort.