Can you tell me about the story of the doctor's nephew from Malegaon and how Udi helped him?

Chapter 34 of the Shri Sai Satcharitra details the story of a doctor from Malegaon whose young nephew suffered from a severe bone-cyst, also known as Hadyavarn. Despite the boy's uncle being a doctor and consulting with many other physicians and surgeons, no native or foreign treatments could cure the ailment. The boy was in immense pain. As a last resort, after hearing of Sai Baba's greatness, the parents traveled to Shirdi. They pleaded with Baba, who, as an embodiment of compassion, reassured them. He gave them Udi and instructed them to apply it to the wound, promising they could now be worry-free.