When 18-year-old Nelima Patel sat down to retake the National Eligibility cum Entrance Test (NEET) medical entrance examination in the western Indian city of Ahmedabad on Sunday, she felt completely drained before the exam had even begun.   The original test in early May was canceled over suspicions that the questions had been leaked. Patel had to prepare all over again, navigating uncertainty, exhaustion and anxiety. "It was mentally exhausting, but I had to keep my wits about me while writing,