Can you tell me the story of the doctor from Malegaon and his nephew's illness as described in the Sai Satcharitra?

Certainly. Chapter 34 of the Sai Satcharitra narrates the story of a degree-holding doctor from Malegaon, in the Nashik district. His young nephew was afflicted with a severe ailment known as a bone-cyst, or Hadyavarn. Despite the fact that the boy's uncle was a physician and consulted with many expert and intelligent surgeons, the disease could not be cured. As stated in the text, they tried all native and foreign treatments, and even surgery, but all efforts were exhausted and nothing succeeded. The boy was in constant pain, causing great distress to his relatives.