Therapeutic query

A patient receiving prednisolone for one year developed oral thrush. He stopped taking prednisolone & took ketoconazole. After 24 hrs, he developed weakness, abdominal pain, fever, nausea, vomitting, diarrhoea, confusion & hypotension. A lot of fluid & electrolytes were supplemented but the condition got deteriorated.

1. What was the cause of symptom to patient ?

2. What should be the line of management in such case ?

3. What are the precautions to prevent it ?